Some 230 British troops have been killed in Afghanistan since 2001
Gordon Brown has insisted that the UK "cannot, must not and will not walk away" from its mission in Afghanistan.
He spoke days after five British soldiers were killed in Helmand by a police officer who was being trained by UK forces.
The future of the UK mission in Afghanistan is being debated in the House of Lords and by military figures.
LORD GUTHRIE - FORMER CHIEF OF DEFENCE STAFF
I do think the servicemen, the people on the front line, are questioning whether the government is really, really committed to making progress in Afghanistan.
COLONEL RICHARD KEMP - FORMER COMMANDER
In order to turn it around we just don't need to explain position strongly as the prime minister is beginning to do now, we also need to do something to turn the situation around, to see real strong results in Afghanistan, which we really haven't seen to date.
That can only be achieved by additional forces and additional resources being put into the campaign.
AFGHAN WAR WIDOW - GEMMA VALENTINE
I just feel if they're not there it seems that the people that have lost their lives have lost their lives in vain. And if we are there it's kind of committing people to the same fate yet again... You don't want to keep see this happening, but there's no easy answer.
LORD KING - FORMER CONSERVATIVE DEFENCE SECRETARY
Counter-insurgency needs local support, and unless the local people think we're going to win and are really committed to doing, you won't get that local support. I see this the last chance to really get a grip on a very dangerous situation.
Of course the lead has to come from the US, of course in that we are a junior partner, but we have a duty. We have a duty to the future defence and security of our country but it won't be the same unless we address the current crisis that we have and deal with it in a much more positive and effective way.
LIBERAL DEMOCRAT LORDS DEFENCE SPOKESMAN - LORD LEE OF TRAFFORD
The primary responsibility lies with Gordon Brown: firstly as chancellor of the exchequer and then as prime minister and first lord of the treasury.
Historically, he's taken little interest in defence, and was semi-detached for too long in the Afghan conflict, with the government being behind the curve re: both troops and equipment all along the line.
Compared with the Falklands - where industry worked around the clock to deliver equipment to the ports with payments sorted out later - there hasn't been anything like the same sense of urgency with the war in Afghanistan.