Barack Obama is coming under mounting international pressure to make an early decision on his strategy in Afghanistan amid fears of a dangerous drift as he agonises over his next moves.
Today Gordon Brown will mount a strong defence of the British presence in Afghanistan. He will say that the training of Afghan security forces by British troops must continue despite the killing of five soldiers by a policeman this week. "We cannot, must not and will not walk away," he will declare. The Prime Minister will not enter the intense debate over whether the US President should approve a request from General Stanley McChrystal, the US commander in Afghanistan, to send 40,000 more troops.
But there is growing concern in London and in Nato governments about the time it is taking for the Obama administration to decide its strategy. "It's make your mind up time," one minister said. A Ministry of Defence source added: "Without a decision there is a concern that the British public will lose faith."
John Hutton, the former Defence Secretary, said: "When you are in the middle of a campaign like this, you have got to make decisions promptly. You need a proper wartime mentality."
Janet Napolitano, the US Homeland Security Secretary, insisted there could be no "rush to judgement" over a question that "deserves full consideration".
In a major speech in London this morning, Mr Brown will declare that Britain is in Afghanistan out of necessity, not choice. He will insist that the war is winnable with the right strategy – building up the Afghan security forces – which is being pursued. He will admit that training the Afghan army and police force is risky but say: "We will not give up this strategy of mentoring, because it is what distinguishes a liberating army from an army of occupation."
Echoing Winston Churchill, he will say: "Just as in the past we learned of the bravery and sacrifice of British soldiers in the first and second world wars; in their fight to protect freedom in our nation and the world; so our children will learn of the heroism of today's men and women fighting in Afghanistan, protecting our nation and the rest of the world from the threat of global terrorism."
Mr Brown will set five tests for the newly re-elected Afghan President Hamid Karzai – and told him about them in a telephone call yesterday. They are: ensuring an extra 134,000 Afghan troops by the end of next year at a rate of 5,000 month, with Britain ready to train 5,000 in Helmand province; leading the fight against corruption, with Mr Brown saying "cronies and warlords" must have no place in the new Afghanistan; bringing moderate elements allied to the Taliban back into the political fold in an act of reconciliation; better use of international aid to ensure economic development and closer co-operation with Pakistan.
Mr Brown will warn that international support depends on the scale of the Afghan President's ambition and how measures up to these five tests. "He needs a contract with the Afghan people; a contract against which Afghans, as well as the international community, can judge his success," he will say.
MPs in all parties believe the killing of the five soldiers may prove a "tipping point" in political and public opinion. A YouGov survey for Channel 4 News found that only 33 per cent of British people believe the Taliban can be defeated, down from 42 per cent two weeks ago, and 35 per cent want troops withdrawn immediately, up 10 points. The Prime Minister will say: "We entered together eight years ago. We must persist together; in our different ways we must all contribute; in the end we will succeed or fail together. We will not be deterred, dissuaded or diverted from taking whatever measures are necessary to protect our security."
Fallen heroes: Tributes to murdered soldiers
'You are my rock, my refuge, and I will love and miss you more than words can say'
Acting Corporal Steven Boote
The 22-year-old from Birkenhead, Liverpool, had volunteered to deploy to Afghanistan, after joining the Territorial Army in 2006.
He had worked as a security team leader at a Tesco store, and had hoped to join the police when he returned to Britain. His girlfiend, Emma Murray, said: "Your cheeky smile would fill everyone with happiness. Steven I love you so much. You are my rock, my refuge and I will love and miss you more than words can say."
Corporal Boote's Company Commander, Major Phil Hacker, said that he "revelled in army life".
"Courageous by nature, he was an outstanding solider who always volunteered for the most difficult tasks," he said. "He inspired confidence in all those he served with and we are all so proud and feel so humble to have served with him."
His parents, Margaret and Anthony, said he would "light up a room with a single smile".
'He ran more than a mile to evacuate me. I owe him everything'
Darren Chant, Warrant Officer Class 1, 1st Battalion The Grenadier Guards
WO1 Chant, from Walthamstow, east London, who was due to become a father for the fourth time, died on the day he was due to be informed he had won a commission as an officer. Earlier this year he had single-handedly carried to safety a colleague whose leg had been blown off in a bomb attack. Fellow Grenadier Guardsman Scott Blaney said: "Drill sergeant Daz Chant put me on his shoulders and ran more than a mile to the point where the chopper had flown to evacuate me. I owe him everything."
His wife, Nausheen Chant, said: "Our unborn son will never meet his father, but he will know him through his legacy. For whether in uniform or out, his incomparable courage and selflessness humbled all those who knew and loved him. I will miss my best friend and nothing will fill the void he has left, my darling Darren. I am immensely proud to say he was my husband."
'I don't know what I'm going to tell my son. I don't want to say nasty men have killed daddy'
Sergeant Matthew Telford, 1st Battalion The Grenadier Guards
The 33-year-old, from Grimsby, joined the army when he was 16. He leaves behind his wife, Kerry, and two sons, Harry and Callum. Mrs Telford said her husband had left a letter for each of them. In Harry's letter he explained why he had gone to Afghanistan and how he was helping people there to live normal lives because they had nobody else to defend them.
Mrs Telford, 33, told the Grimsby Telegraph: "I don't know what I'm going to say to him. I don't want to say that nasty men have killed daddy – I want to be able to tell him that he's in heaven now and has gone to be with the angels."
Described as a "gentle giant", Sgt Telford died while working as a mentor for the Afghan police. Captain Bernie Broad, Quartermaster Technical, First Battalion Grenadier Guards, said: "A larger than life character, he was large, fit and intelligent. Throughout his career his enthusiasm for the job never diminished and with his excellent sense of humour and gentle touch for such a giant of a man, he was known, respected, and trusted by all."
'You always think it might happen, but we only spoke to him on Tuesday night'
Guardsman James Major
The teenager from Grimsby would have turned 19 next Thursday. His family had recently sent presents to Afghanistan. His father, Adrian, said: "I'm just shell shocked. You always think it might happen but we only spoke to him on the Tuesday night." He completed his infantry training in November last year.
On the day his son left for Afghanistan, Mr Major had hung a Union flag on the side of the house. Many people have left cards and flowers there over the last two days. One reads: "You are a true hero. God bless you. Love from a mother of a serving soldier in Afghanistan." Other well-wishers had left a football emblazoned with messages of condolences and a teddy bear embroidered with the words "I love you".
Lance Sergeant Peter Baily, Signaller, Commanding Officer's Tactical Command Group, said Guardsman Major "immediately came across as a very intelligent and motivated soldier – a quiet soldier at first, but he came out of his shell quickly and showed a rare comical side that kept the rest of the TAC group in high spirits."
'He was one of the most loving, generous and kind-hearted men you will ever meet'
Corporal Nicholas Webster-Smith
The corporal, 24, was born in Carmarthen, Wales, and lived in Brackley, Northamptonshire. He enlisted in the Royal Military Police in 2005 and had already completed a tour of Afghanistan. He had also served in Kosovo and the Falkland Islands, where he was awarded a Commander British Forces Falkland Islands Commendation.
Among messages left on his facebook page, his girlfriend Emma Robinson said: "I love you so much and just can't believe this is happening. You have made me so happy and we have had so many happy memories together which will never be forgotten. I love you always."
In a statement from the Ministry of Defence, his family said he was "one of the most loving, generous, kind-hearted men you could meet".
His Commanding Officer, Lieutenant Colonel Debbie Poneskis (Commanding Officer 4th Battalion Royal Military Police), described Cpl Webster-Smith as a "real character".
"A professional and determined soldier, Cpl Webster-Smith was always the first to volunteer and the last to give up," she said. "A spirited non-commissioned officer with a keen sense of humour, Cpl Webster-Smith was at his most comfortable in the midst of fellow soldiers, either guiding and mentoring them, or having a laugh and a joke with them."