The head of the armed forces has told the BBC that the British military has "succeeded" in its mission objectives in southern Iraq.
Sir Jock said the British had succeeded in southern Iraq
Air Chief Marshal Sir Jock Stirrup said the army had "very nearly" reached its target of allowing Iraqis to run that part of the country.
Sir Jock also said while the operation in Afghanistan was "entirely winnable" it was "entirely loseable" too.
But he said he thought the armed forces could cope with being stretched.
He told BBC Radio 4's The World at One that opinions on southern Iraq depended "upon what your interpretation of the mission was in the first place".
He said: "I'm afraid people had, in many instances, unrealistic aspirations for Iraq, and for the south of Iraq.
"Our mission there was to get the place and the people to a state where the Iraqis could run that part of the country, if they chose to, and we're very nearly there.
"Our mission was not to make the place look like somewhere green and peaceful, because that was never going to be achievable in that timescale.
"And in any event only the Iraqis can fulfil that aspiration."
Sir Jock also said that he expected the British army would hand over control of Basra to Iraqi forces "in the near future".
He said: "It hasn't been decided yet, it will come up for consideration within the next couple of months, I suspect, but I am fairly confident that we should be able to achieve that position in the second half of the year."
The chief of defence staff also admitted that the conflict in Iraq and Afghanistan "had an effect" on radicalisation of people in Britain, but that it was not the root cause of the issue.
"I think it is likely that there is some effect, but they are not the cause. Radicalisation was there before those conflicts existed.
"Clearly one couldn't deny that there may well be some kind of relationship between the two."
Sir Jock also spoke of "ungoverned spaces" such as those found in parts of Afghanistan.
"If you allow ungoverned spaces to exist around the world, then radicalisation is likely to become greater.
"Tackling those ungoverned spaces is a really tough problem, but a failure to tackle them is much more likely to lead to a rise in radicalism and its consequent effects."
The head of the armed forces described the ongoing operation in Afghanistan as "entirely winnable" but also admitted it was "entirely loseable" too.
"The mission in Afghanistan is all about governance. We're trying to help the government of Afghanistan extend its rule into parts of the country where, frankly, it has just not run before."
Benefits and drawbacks
And Sir Jock appeared to disagree with the assessment of the head of the army, Richard Dannatt, that the British presence in Iraq had exacerbated the violence among insurgent groups.
"When you have a foreign military presence in a country, even if it's welcomed in the first place, over time, you lose consent.
"People want to get on with their own lives. They don't want somebody else governing and garrisoning their country.
The number of British troops stationed in Iraq is due to fall
"At the same time, that presence of other troops helps to stabilise the situation and create the kind of security environment in which a political process can move forward.
"So you have benefits but you have drawbacks.
"And the question is at what stage do the drawbacks start to outweigh the benefits? It's not a question of there being no drawbacks - it's a question of the balance between the two."
Sir Jock Stirrup has previously told parliament's defence committee there was "not much more left in the locker" when it came to the nation's armed forces, which were "very stretched".
His comments have been echoed by UK armed forces minister Bob Ainsworth, and in a leaked memo, Gen Sir Richard Dannatt warned that British troops are so stretched that the nation's military reserves are "almost non-existent" because of the operations in Iraq and Afghanistan.
Sir Jock said: "We are very stretched, because just at the moment we are doing more than we are structured or resourced to do in the long term.
"Now, we can do that in the short term. We can surge to that degree. But sooner or later we have to get back into balance.
"And the longer it takes to get back into balance, then the longer the recovery time becomes. Having said that, of course, we are now on a downward path in terms of operational tempo.
"We've removed our combat troops from Bosnia, and as you've seen - we've actually reduced our force levels in Iraq.
"We're down to about 5,500 troops in the south east."
The government has announced that UK troop levels in the Basra area are to be cut by to 5,000 by the end of the year.
Sir Jock Stirrup said he was "frustrated" that Nato's minimum troop requirements had not been met.
"Of course I am frustrated that Nato has not managed to fill the minimum requirement but this is a very complex area and different countries take a different view.
"What I think is important is that the international community as a whole puts enough effort into Afghanistan.
"Some of it has got to be military and it would be nice if people would do more on the military front.
"But if they are not going to do more on the military front I think they should be doing more on other fronts, in terms of development, developing the police, in terms of developing civil society.
"This is a mission that can't be delivered just by the military, it's got to be delivered by a co-ordinated international and Afghanistan effort across all areas of governance."