British forces will not remain in Afghanistan for "a day longer than is necessary", the Prime Minister told MPs today.
In a Commons statement after his visit to Afghanistan last week, David Cameron said: "I want to bring them home the moment it is safe to do so."
But he stressed that day had not yet arrived and insisted the current year was a "vital one" in securing the coalition's strategy.
Mr Cameron warned of further British casualties over the summer months, as the "so-called fighting season resumes".
He said the troops were there to "protect our national security here at home" but would come back when the Afghans were able to take control of their own security.
The threat from al Qaida in Afghanistan and Pakistan had reduced, Mr Cameron conceded.
"But I am also advised that if it were not for the current presence of UK and international coalition forces, al Qaida would return to Afghanistan and the threat to the UK would rise."
Acting Labour leader Harriet Harman promised full support for the Government's strategy as ministers proceed to take "difficult decisions" in the months ahead.
Mr Cameron promised MPs regular updates on the security situation in Afghanistan after his fifth visit to the strife-torn country and first as Prime Minister.
"Why are we in Afghanistan?" he asked. "I can answer in two words: national security.
"Our forces are in Afghanistan to prevent Afghan territory from again being used by al Qaida as a base from which to plan attacks on the UK and our allies."
Afghanistan was not yet strong enough to look after its own security. "That is why we are there.
"And together with the greater efforts of the Pakistanis to hunt down al Qaida in their own country, al Qaida are now under pressure on both sides of the border."
Mr Cameron said people were rightly impatient for progress. "Our forces will not remain in Afghanistan a day longer than is necessary and I want to bring them home the moment it is safe to do so."
The key to this was training and equipping the Afghan security forces.
He said: "The current year is the vital one. We are six months into an 18-month military surge and we must now redouble our efforts to drive progress."
Some "real progress" had been made in central Helmand this year, with a "degree of normal life" returning to places like Nad Ali.
"But the progress is not yet irreversible. Inevitably there will be tough fighting as Afghan forces, with Isaf in support, hold the ground we have taken and push the insurgents out of further towns and villages."Reuse content