By John Pienaar in Trinidad
Political correspondent, BBC News
Prime Minister Gordon Brown is under pressure over Afghanistan
Gordon Brown has clearly decided it's time to add urgency and method to the international effort to hand control of Afghanistan to the Afghans.
His tone in setting down terms for co-operation with Hamid Karzai's government has never been more forceful.
The prime minister has been accused by critics of presiding over a mission with unclear aims, and beginning to drift.
Was it driven by the need to deny terrorists a safe haven from which to plan and launch attacks on the UK and its allies? Was it about establishing a functioning democracy in Afghanistan, purged of corruption and endowed with traditions of equality and justice?
And crucially, was it geared to enable Afghanistan to manage its own security within a realistic timetable?
Gordon Brown has now attempted to show all these aims are interlinked, and progress in achieving them will be measured as a condition of British and other troops continuing to risk - and lose - their lives in the Afghan cause.
Conceivably, the newly re-elected Afghan president may resent being handed his marching orders in this way. But the prime minister's tone implied he was not overly concerned with Hamid Karzai's sensitivities.
And Mr Brown is under a good deal of pressure on his own account. British public opinion has been growing steadily more sceptical towards the Afghan mission.
Hamid Karzai is under pressure to bring order to Afghanistan
Constant suggestions that British troops have lacked necessary equipment - helicopters in particular - have taken their toll, despite ministerial denials.
The prime minister will be hoping this tough new tone wins over a few British doubters. He seemed confident that the international conference on 28 January next year would bring with it fresh promises of troops.
He seemed on course to confirm 500 more British troops would join the 9,000 already serving in Afghanistan in a statement to the Commons next week.
Mr Brown was offering no timetable for withdrawing those troops, and insisted he would not be doing so.
But an assessment of progress by the end of 2010, he suggested, might finally place the scale of British involvement on the agenda.
The existence of "benchmarks" for progress might also help him as he deals with an inevitably rising casualty list, and an increasingly sceptical public in the run up to the 2010 general election.