The US and UK have been urging other Nato countries to share more of the combat burden in the south of Afghanistan.
Britain has around 7,800 troops fighting in southern Afghanistan
BBC correspondents sum up viewpoints from different troop-contributing countries to the international military operation.
LEE CARTER - CANADA
The Canadian Prime Minister Stephen Harper has made it clear that he is ready to put the future of the country's mission in Afghanistan to a confidence vote, a move that may trigger a general election.
Canada has 2,500 soldiers stationed in Kandahar, where they are engaged in direct combat operations against the Taleban.
Canadian soldiers are mainly based around Kandahar
Some 78 Canadian soldiers have died in Afghanistan since their mission began there in 2002, many in roadside bomb attacks.
Many Canadians feel that their troops are disproportionately taking casualties, while other Nato members are declining to put their troops in harm's way.
Last week, Mr Harper delivered an ultimatum, saying he would pull Canada's soldiers out of Kandahar early next year, unless Nato sends at least 1,000 extra troops.
Mr Harper's minority government has unwaveringly supported the mission and wants parliament to approve extending it.
Liberal leader Stephane Dion, by contrast, says he will not compromise on his position that Canada should end its combat role in Afghanistan - but there are reports that not every Liberal agrees with him.
Public opinion has been similarly divided over the war, although the latest Angus Reid opinion poll suggests there has been an increase in support for the Afghan mission since last summer.
When asked if Canada should extend its mission, 36% said they agreed, up from 16% last July.
HUGH SCHOFIELD - FRANCE
Ask most French people about the country's troop commitment in Afghanistan, and they will have little idea what you are talking about.
This is despite the fact that some 1,600 soldiers are currently deployed with Nato in Afghanistan, that 13 French soldiers have been killed in the last five years, and that French jets have had an active role in the fighting in the south of the country.
The reason for the lack of awareness is the lack of coverage in the national media, and this is itself linked to the fact that most French soldiers in Afghanistan work in the relatively safe environs of Kabul.
There are no graphic accounts of life on the front line as are now regular fodder in the British, Canadian and American press.
President Nicolas Sarkozy, who visited Afghanistan before Christmas, has said the war against the Taleban is one that "we cannot lose". He wants France to play a much bigger role inside Nato as part of his overall foreign policy.
In recent days his government has hinted it may look favourably on a request for more manpower in Afghanistan. But whether or not this would involve an active combat role, and how the French public might respond, remains to be seen.
TRISTANA MOORE - GERMANY
Despite growing pressure to send combat troops to southern Afghanistan, the German government is refusing to change its position - German soldiers will remain in the north and continue to observe their parliamentary mandate.
Germany has said it is doing all it can in northern Afghanistan
Germany has around 3,300 troops in Afghanistan - mainly deployed in the relative safety of the north and near the capital Kabul.
The focus of the mission is on reconstruction and development and not combat.
According to the remit of the mission, German troops can only be sent to the south in emergencies.
The German defence minister has confirmed that Berlin is going to send an extra 200 troops to serve as part of a quick reaction force in northern Afghanistan, to replace a Norwegian contingent in the summer.
Their main tasks are to conduct patrols and provide security and crowd control, as well as mount evacuation and search operations.
Although there are some dissenting MPs, there is broad political consensus for the current remit of the Afghan mission.
But in terms of public attitudes, the German mission in Afghanistan remains very unpopular and many people oppose a deployment of troops in the south of the country.
A recent opinion poll suggested that the majority of Germans believe that the Bundeswehr is right to steer clear of the more volatile south.
With the news that Germany is sending troops to serve in the quick reaction force, some commentators expressed their concerns that the soldiers would be sucked into combat operations, exceeding their current mandate.
But others argue that Nato is facing the risk of failure in Afghanistan and the German government should change course and send troops to the south of the country.
Last autumn, the German parliament extended the mandate of the Afghan mission by another year. Given the shaky public support for the entire mission, it is unlikely there will be any big changes in the near future.
CHRISTIAN FRASER - ITALY
Italy has come under increasing pressure from its Nato allies to increase its commitment to Afghanistan.
Last year the US ambassador to Italy, Ronald Spogli, and five other ambassadors stirred controversy when they sent a letter to a national newspaper calling for an "increase in the contribution for reconstruction and civil development".
Mr Berlusconi unlikely to risk his re-election by pledging more troops
Italy has 2,290 troops in Afghanistan, most of them stationed in the western province of Herat.
Despite pressure from within the ruling coalition, the government has given the Afghan President Hamid Karzai assurances that it will stick to its key commitments until 2011 - even though public support is waning.
In one poll carried out by Italian magazine Panorama, 56% of people questioned said they wanted troops withdrawn.
There are elections looming in Italy which could have an impact on the country's future involvement. At the last election the centre-left pledged to pull 2,300 troops out of Iraq.
Romano Prodi made good on that promise within six months - although in truth it was his predecessor, Silvio Berlusconi, who had started the initial withdrawal.
Mr Berlusconi, now well ahead in the polls, is seen in Washington as one of their more reliable allies. He had supported the war in Iraq.
But, in the face of such public opposition to the Afghan mission, it is unlikely he will endanger his election by pledging to send more troops - or changing the remit of those already there.
SARAH RAINSFORD - TURKEY
Turkey has contributed troops to the Isaf mission in Afghanistan since the start and led Isaf twice - in 2002 and 2005.
It has approximately 1,150 personnel in Afghanistan, according to the website of the chief of staff.
Turkey has also established a joint civilian and military team in Wardak province, close to Kabul, engaged in reconstruction and infrastructure work and training local Afghan police.
The deployment - as it stands - is uncontroversial here. The troops are in the relatively safe region around Kabul and do not participate in combat operations.
No Turkish soldier has been killed in Afghanistan since troops went in over six years ago, according to Hikmet Cetin - Nato's former senior civilian representative in the country, and a Turk. (His name has recently been discussed as a possible candidate for the post of UN envoy to Afghanistan.)
Analysts here believe Turkey, as a Nato member, is committed to maintaining its current contribution to the international military presence in Afghanistan.
However Ankara is unlikely to go any further. Last year, Turkey's top general ruled that out explicitly and has given no indication since that his view has changed.
Turkish troops are already heavily deployed at home, fighting the Kurdish separatist PKK in the south-east and launching air strikes on suspected PKK targets in Northern Iraq.
Their deployment in Afghanistan is not a "hot" public issue at the moment. But any change that further endangered Turkish lives, fighting in another Muslim country, would be controversial.
NAOMI GRIMLEY - UNITED KINGDOM
It is not easy to know where British public opinion on the war in Afghanistan actually stands at the moment.
The last poll (by YouGov) on the subject was six months ago. That suggested that 27% of the public wanted the troops home immediately. Another 37% wanted them back in the next year or so.
British politicians - who still predominantly back the war - point to the fact that public support for military action in Afghanistan has always been more solid than it was for the war in Iraq.
But even members of parliament who want Britain to stay in Afghanistan fear that public opinion and political could waver.
"The political will is there," says James Arbuthnot, chairman of the House of Commons defence committee.
"First, we don't want to see another 9/11. Second, 90% of the heroin on our streets comes from Afghanistan."
"But that political commitment is weakened by questions about whether we are actually doing the right things to solve those two problems."
Those calling for a complete withdrawal of British troops say the argument is now shifting their way.
Paul Flynn, a Labour member of parliament, thinks there might be a backlash after Afghanistan's president, Hamid Karzai, suggested that the British army had caused insecurity in Helmand province.
"That's outrageous," Mr Flynn says. "If Britain is giving its blood, that ingratitude will swing public opinion away from the war."
BRIDGET KENDALL - BBC DIPLOMATIC CORRESPONDENT - UNITED STATES
Of all the Nato allies, the US has the largest number of troops in Afghanistan - upwards of 27,000 - and, with a death toll of some 480 so far, it has sustained the greatest number of casualties.
Only half the American contingent is part of Nato's Isaf force.
In the US, Afghanistan is seen as a counterterrorism operation
The rest operate separately in the far less high profile US-led counter-terrorism force known as Operation Enduring Freedom, whose task since 2001 has been to hunt down al-Qaeda insurgents and keep up the so far fruitless search for Osama Bin Laden.
There is little doubt of the US administration's commitment to keep troops in Afghanistan for the long term, and even provide more for the Nato operation when needed.
Washington has already announced plans to send an additional 3,200 marines for a six-month spell starting this spring.
Both the US Defence Secretary Robert Gates and the Secretary of State Condoleezza Rice have made it clear they expect other Nato allies to follow the US example.
"I worry a great deal about the alliance evolving into a two-tiered alliance, in which you have some allies willing to fight and die to protect people's security and others who are not," Mr Gates told US Congress this week.
For the US, this is a far less controversial deployment than the war in Iraq.
No doubt this is because the cost - in terms of lives lost and money spent - is far lower. Unlike the war in Iraq, Afghanistan does not even figure as a separate issue on most Americans' lists of top political concerns.
Recent comments by top US commanders and some prominent analysts paint an increasingly bleak assessment of the challenges ahead.
But opinion polls suggest most Americans still think the conflict in Afghanistan - seen by and large as a counterterrorist campaign - is worth supporting.