Click here to listen to Jonathan Marcus answering your questions

He became the BBC's Defence Correspondent in 1991 having been Transport Correspondent and a reporter before that.

He has covered the development of the Balkan conflict since that time as well as the Gulf War and other conflicts.

Read below a full transcription of Jonathan Marcus's replies to your questions.

Paul Cassidy, Netherlands: Britain has been involved in a number of small conflicts in recent years, and the armed forces are very stretched. Do you think that Britain needs to spend more on defence if we are to meet our military commitments and requirements?

Jonathan Marcus: It's quite clear Britain with its all professional armed forces has some of the best equipped and most deployable forces in Europe, I think the best indication of that is the French are following the British model. One of the good pieces of news for the British armed forces is the much reduced commitment in Northern Ireland - that was the thing that was over-stretching military resources extraordinarily.

I think operations in Bosnia and potentially in Kosovo are about the limit of what Britain could do. On the air front it is obviously operating missions in the Gulf still and it is also making a commitment, albeit small, in Kosovo. I think this conflict is seen as proving the validity of the underpinning of Britain's recent strategic defence review. The key thing will be whether the Defence Ministry can ensure all the money allocated can be spent on the right sort of equipment and training and so on.

Paul Carroll, Scotland: Why, if the intelligence knew about imminent ethnic cleansing, did UN remove monitors from Kosovo rather than increase them?

Jonathan Marcus: It was clearly impossible for the monitors to stay given the upsurge in fighting, the Belgrade government wasn't very happy about having them there and so on. In a sense the monitors were supposed to be the eyes and ears for the international community to warn of what be taking place in Kosovo.

Now those warnings at least of some ethnic cleansing and some continuing fighting between the KLA and the Yugoslav forces which inevitably drew in the villages, meant civilian populations were cleared and so on.

That was a warning that the civilian monitors gave very clearly, I think having received that warning Nato then finally, after making repeated threats against Mr Milosevic, finally felt that at the end of the day that it just had to act and its credibility was on the line and of course many commentators have criticised the way in which Nato rather stumbled into all of this. Some people are of course arguing that Nato should have used military force much earlier. In the event they didn't and we've obviously seen now the consequences of their actions.

D Turner, UK: Do you think Nato's priority is getting the refugees out of camps and back home before winter, or drifting along with the current low risk, low return strategy of air strikes?

Jonathan Marcus:Clearly they'd like to get the refugees back home as soon as possible, it may prove very difficult to get them back before winter unless Yugoslav forces are withdrawn, and then that is going to require a huge logistical and engineering effort to restore water supplies, provide shelter etc. It's different I think from the case in Bosnia when in many cases refugees wanted to return home, they found people from other ethnic groups living in their homes.

I think it is, if you like, a low risk strategy for Nato. The problem of course is this is a committee of 19 democratic governments all of whom have different opinions within their own countries. This is a very different sort of warfare.

It's been criticised by many military people and in the media but one has to understand that given the diversity of the governments involved this may be the lowest common denominator, and they never imagined Mr Milosevic would still be keeping his forces in Kosovo after Nato struck. Now they are into a strategy of damaging his forces and infrastructure sufficiently to compel him to back down, again a something of an uncertain goal.

Dejan Mihailovic, Belgium: What do you think of the Serb reports that many more Nato aircraft have been shot down? After such long and intensive bombing campaign it is impossible that only two were downed as NATO claims.

Jonathan Marcus: I think it is, I discount those claims completely on the occasions that the Yugoslavs have claimed accurately that Nato warplanes have been shot down. We've all seen the film on Belgrade Television very quickly of the wreckage. I think it all comes down to a very simple fundamental factor.

You have 19 democracies waging this war against a country that has a very restricted and authoritarian political system. The media in all of the 19 countries are free. You can listen to people's briefings, you can check out the information on background and conversations with other people, you can compare what they are saying in different capitals and so on.

On the simple issue of aircrew being lost - I think it's absolutely clear - if aircrew were being lost, if they had fallen into Yugoslav hands or they'd been killed, then their families and colleagues would know about it.

You're dealing with two very different sets of actors in this campaign, and of course that greatly complicates how one can report it, the access to information you have on both sides and so on. But a judgement has to be made. My judgement is that when Nato loses planes, it says so, because that is the nature of the socities that the Nato countries are.

Robert Kloosterhuis, Netherlands: With heavy negotiations going on, on the political front, is there in your opinion still a possibility of a ground invasion of Kosovo? Is ground intervention still being considered by Nato commanders? And if it is, when do you think Nato will make its move?

Jonathan Marcus:Ground intervention is the great divisive issue within the Alliance. Everyone can agree on the air campaign but they can't agree on the use of ground troops, when they should be deployed, whether they should do any fighting etc. What they do agree on is at the end of the conflict a large number of Nato troops will be part of some international force on the ground in Kosovo, helping to ensure the security and stability of the province to enable refugees to return home.

Whether those troops might actually move in prior to a full withdrawl of Yugoslav forces is an issue Nato simply doesn't want to address at the moment because of the different views in different Nato capitals and of course increasingly Nato has to keep the Russians on board.

Mark M. Newdick, USA: I find it amazing that the Serb public and their politicians are still in "denial" over the atrocities committed in Kosovo ... according to interviews on TV here, and the Serbian website. This "war of words" is clearly something that Nato is not winning inside Serbia, and is fundamental to detaching Milosevic from the people he governs. I agree that shutting down his broadcast media might help, what is Nato doing to change this?

Jonathan Marcus: Well it's very difficult. Clearly there are a large number of international broadcasters who are broadcasting in the local languages into Yugoslavia. People today now have extraordinary access via the Internet if they have access to a computer, so by not everyone by all means is cut off from outside information.

I think though inevitably the country feels it is under attack, it is under attack. Whatever people may think of Mr Milosevic, clearly the initial response is to hunker down, to support your country, to see it as your country in danger fighting outside forces.

I think though as the casualty tolls mount, as the damage increasingly is inflicted on Yugoslav forces in Kosovo itself, I think the message gradually will spread throughout the Yugoslav population, clearly turning off the power which has been done now on a number of occasions, brings home to ordinary people right into their homes the ability of Nato's air campaign, as the Nato spokesman is said to have its finger on the switch of power generating in Yugoslavia.

I think it can hardly be likely, given the fact that ethnic cleansing has gone in this region, and against the Serbs as well, but it has gone on in this region certainly authored by Yugoslav forces on a number of other occasions. People in Yugoslavia deep down must know the sorts of things that the soldiers and their paramilitary forces are getting up to in Kosovo.

N. Harrison-Roberts, Germany: Why does Nato take such an interest in the Balkans, yet completely ignore the plight of the Kurdish people? There have been many substantiated reports of chemical weapons and ethnic cleansing in this area but nothing has been said or done. To many this appears a serious case of double-standards.

Jonathan Marcus: I can understand that criticism and if NATO were setting itself up to be in some way to be in the broader sense an international policeman I think that quite clearly it should intervene in a whole range of areas. I think that the problem is that by intervening in one and not intervening in others that doesn't necessarily lead to a decision logically that the intervention in that single case is a bad idea.

Nato believes that there were pressing reasons for it to act in the Balkans, not least because of its very strong commitment in Bosnia, with its new member Hungary now bordering Yugoslavia. And I think, quite apart from the geo-strategic aspects, there are concerns about two key NATO members, Greece and Turkey, perhaps being drawn into this conflict as instability in the Balkans spreads.

I think there was, rightly or wrongly, a moral dimension and we have, now at the end of the century, been looking back over the troubled decades, back to the second World War, back to the horrific events that have happened in our century. I think that the fact that these events happened in Kosovo when they did meant that, as Bill Clinton said, that there is a sense that history will be changed here, that things that went on earlier in the century will be changed in the Balkans. Now whether NATO is really able to do that, or whether that is really a reasonable point of view is really it is clearly not for me to say. That is a stand that comes out very strongly in the rhetoric from many of the Western leaders, not least Bill Clinton and the British Prime Minister Tony Blair.

Gerard Dorrity, Italy: As someone who teaches English to Italian Army officers, I'd be interested to know how much of an obstacle, if any, language knowledge presents to the smooth running of this Nato operation.

Jonathan Marcus: Well I don't think it does because I think clearly in purely political terms Nato has two languages - French and English. I'm sure people have seen the press conferences where the Nato spokesmen are expected if not to answer questions in French, at least to be able to take questions in French as well as English.

On the military front it's not problem at all because the language of command is English. As you can imagine, although there are extraordinary levels of technical proficiency, running an air campaign like this is an amazingly complicated task. You couldn't do it if people were all speaking different languages. I think, as most people know, the international language, even of civil aviation is English, and that is the main language of command.

Stephen Block, US: I am not aware of the legality of Tony Blair's dispatching troops to a war without some form of authorisation such as from the Queen or Parliament. Clinton has launched his war without either Congress authorisation as mandated by our Constitution or the approval of the UN which is the organisation set up in 1945 to prevent wars. Will either Blair or Clinton get the legal support for their actions?

Jonathan Marcus: Well, this operation has obviously gone ahead without any UN resolution. This was one of the main concerns of Russia, of course Russia and probably China too would have vetoed any resolution. All the NATO countries believed that they had sufficient justification in international law to act.

The situations in United States and Britain are very different. In Britain you don't have the same separations of power that you have in the United States, you don't have anything quite like the war powers resolution which was meant to try to limit a president's ability to deploy forces to a war in the wake of the Vietnam conflict. Of course that hasn't been used very often and in fact America has sent troops to many, many conflicts without declaring war.

It has to be said that most of the NATO leaders don't believe that they are fighting a war. They keep on insisting that they are fighting an air campaign and that this is not a war. But I think that there is another very interesting debate that is worth mentioning. That's the old debate about national sovereignty.

I think in a sense the Cold War kept a straight jacket on the concept of national sovereignty. What a country did to its own people, in its own country, inside its own frontiers was basically its own business however much people may have disapproved. They could apply economic sanctions or whatever but they couldn't do anything about it. In the wake of the cold war I think there are very new ideas of sovereignty being developed. One is that sovereignty is not an absolute idea and one that says that there is a right of humanitarian intervention. It's a very prominent idea on the French left and of the Third way governments of Bill Clinton and Tony Blair. I think that is one of the reasons why they believe that they are acting justifiably in the Balkans.

Tonio Galea, Malta: The weather factor is mentioned many times as the reason for the postponement of Nato attacks. How credible do you think this is particularly when one considers that Nato's warplanes were built to counter the Soviet threat - a region that has far worse weather than the Balkans?

Jonathan Marcus: Well that I think really gets to the nature of the conflict that is being waged here. Clearly in a full scale war against the Soviet Union far greater risks would have been taken to Nato pilots, there would be far less concern when Nato pilots actually dropped weapons as to who they were going to hit and where they were going to land. Clearly in that sort of conflict the problems with the weather would have affected the Soviet air forces as well. It would have been the same for both sides.

I think one must remember the extraordinary constraints that are being applied in this campaign. Now that doesn't mean that civilians are not being killed, it would be ridiculous to suggest that that was the case. There are civilian casualties in Serbia and Kosovo, but Nato is trying very hard to reduce them to a minimum, that means its using almost exclusively precision guided weapons.

Many of those weapons actually require the pilot to be able to see visibly with his eyes the target. Now if you have cloud covering the mountain tops, cloud rolling into the valleys, as you did for much of March and April, particularly in the attacks against Yugoslav forces in Kosovo itself, it was virtually impossible for Nato to see anything. Given the constraints and their desire to avoid civilian casualties, planes were more often than not returning with their bomb loads in tact. I think that is the very peculiar nature of this air campaign.

But now the weather is getting better and a whole range of systems have been bought into the theatre of operations that don't necessarily need a line of sight to the target.

Tot Ivan, Yugoslavia: Is it true that NATO is running out of cruise missiles and will be therefore less precise and cause more tragedies to civilian population in Yugoslavia?

Jonathan Marcus: Its certainly true that some of the key weapon systems being used by the Americans - particularly the ones guided to their targets by satellite systems, the GPS - there aren't huge quantities of those weapons. The Americans are tying to convert other weapons to that capability, to try to go to industry and get them to do things quickly.

But remember the weather is improving and that means that many of the more traditional precision weapons that use lasers are being used and in the last few days we've seen employment of more dumb bombs, unguided bombs, particularly by the American B52 bombers flying out of England. The navigation systems on board the B52s today mean that even with unguided bombs they can drop those weapons into a relatively small area with a high degree of accuracy, but weapons go wrong, people are fallible and the technology doesn't always work. But Nato believes that in 95% plus of cases weapons have steered to their correct target.

Tom Stelter, USA: How is the cost of Nato operations being borne? Is the USA and England paying for all the bombs they drop or are the rest of the Nato countries sharing the cost? If they are sharing what are the percentages?

Jonathan Marcus: No, I think everybody pays for the contribution that they make. Clearly the costs for certain countries are much greater than others. If you look at the case of Italy, which is not a huge contributor actually to the air operations in terms of flying the bombing missions. Nonetheless its whole country is being used as one vast Nato airfield. Civilian airports along the eastern seaboard of Italy have all been closed down. We are now approaching the holiday season, I'm sure it's going to have huge economic impacts on those communities down the coast of Italy.

Clearly there is going to be vast spending in the wake of this operation both in military terms in replenishing stocks and trying to apply some of the lessons learnt from this conflict, but obviously massive massive costs for actually deploying a force in Kosovo if that is how it ends, in helping to rebuild the shattered infrastructure in Kosovo. That clearly is going to be a job that goes way beyond Nato's capabilities, that is going to be something for the major industrial nations, for international financial institutions and so on.

S Henderson, USA: In carrying out your coverage how often do you get out of Brussels? is your reporting all based on Nato official information?

Jonathan Marcus: I've been here for pretty well most of the air campaign, I've been back for a few days on the odd occasion to London and I was in Washington for the Nato summit which punctuated one stage of the air campaign. Inevitably one is drawing on a variety of sources. There are essentially three Nato briefings to the public each day, one here in Brussels, one in London and one in the United States. All of these are very different in there own ways, they have different levels of information, different levels of panache in their presentation. In Brussels we have Nato spokesman, Jamie Shea, who has become a bit of a media personality during this war; in London we have well-orchestrated press conferences with live satellite links to Macedonia or Albania; Pentagon briefings are drier but with masses of military information. In addition to that, one speaks to people, both Nato and outside Nato.

There are vast arrays of information - speaking to people on the internet etc, you can even find out information about the weather on the internet. Myself and my colleagues, the first thing we do each morning is call up a website with a satellite picture of the weather perhaps a few hours before, and that gives a very good indication of how much military activity, particularly over Kosovo, there may have been the night before.

Thomas D. Tynan, Ireland: In light of the performance of the Apache helicopters, i.e. three have crashed, will they be the miracle weapon the media has suggested they would be?

Jonathan Marcus: No they won't be the miracle weapon. There was this feeling that they were the silver bullet, as it's called, that would end the conflict once and for all. I think two have actually crashed, not three. The Apache is an extremely potent weapon, destroying tanks and armoured vehicles in the field, and can do so at great range and it was very successful in the Gulf War.

What's going on at the moment is the pilots are training intensively to operate in the sort of terrain that you have in Albania and in the border region between Albania and Kosovo itself. I think that intensive training at low level, at night, using night vision goggles, explains in part why the two helicopters have gone down. I don't think these accidents are that extraordinary, they're obviously very unfortunate for the colleagues and families of those concerned.

I think that the problem with using the Apache, is in military terms that it is intended to fight ahead of its own front line. The problem for the use of the Apaches in Kosovo is that if they venture very far into Kosovo, the very dispersed nature of the Yugoslav forces means that these helicopters could face anti aircraft funs from a whole 360 degree radius from around them, which really makes them very vulnerable. I think if and when they are used, we're probably likely to see them used by just making small incursions into Kosovo across the frontier rather than ranging very deeply into territory which has large quantities of Yugoslav dispersed forces.

David, Canada: Why hasn't NATO targeted the Serb leadership?

Jonathan Marcus: This is a great problem for most ordinary people - they would logically argue, if you don't like what Mr Milosevic is doing why don't you blow up him instead of targeting all sorts of facilities which inevitably will lead to some civilian casualties. The United States has this seeming constitutional prohibition on taking out the leadership of countries although if they were killed in some sort of air-raid not too many people would shed many tears.

But basically the Nato position is that it is not trying to change the regime in Yugoslavia it is trying to change the behaviour of that regime. It would obviously like Mr Milosevic to disappear and if he is still there at the end of all this it is obviously going to have a problem. Nato has demonised Mr Milosevic, it says Mr Milosevic is the guiding hand behind all the horrific things that have gone on in Kosovo. That clearly implies that he might be potentially indicted as a war criminal himself by the War Crimes Tribunal in the Hague. So how are they going to negotiate with this man, if there is going to be a final diplomatic solution, when they know the sort of person he is and what ultimately might happen to him? So I think you have to disentangle the rhetoric from the hard practical realities of having to deal with all sorts of people you ultimately may not particularly like.

J Gregory, UK: As the conflict within the former Yugoslavia changes and hopefully turns a corner, what can be done to stabilise the region especially Montenegro and Macedonia to ensure Milosevic does not continue to reap violence and devastation where he likes?

Jonathan Marcus: Well that's going to be a very important part of the post-war settlement for the region. I think we're going to see Nato troops in many of these countries for some considerable time to come, and also obviously they're in Bosnia. I think we're going to see broad economic frameworks and packages for the region.

After all the tragedy maybe it will benefit the Balkans, because this is a region which has been totally peripheral to most of the developments over much of this century. The twentieth century began with conflict in the Balkans and it's ending with conflict in the Balkans. Perhaps the result of all this will be to bring these countries closer to the European mainstream, to bind them into a group of more democratic countries. Hopefully it will give them the economic development that they so badly need.

Jonathan Howell-Jones, UK: Does the Balkans question pose a serious threat to the unity and existence of Nato and future Nato operations?