Lord Ashdown (L) and Nick Clegg want to see a united strategy
The war in Afghanistan cannot be won unless current policies are changed, the Liberal Democrats have said.
In a joint newspaper article, party leader Nick Clegg and former leader Lord Ashdown accuse the international community of lacking a united strategy.
The article, in the Guardian, says Nato is "a hotch potch of the committed and the half hearted" and calls for the UK to appoint an Afghanistan minister.
They also call for a war cabinet to be established by the UK government.
Their article says the UK government needs to "change gear".
"The prime minister needs to make it clear that this struggle is now the nation's priority and we will strain every sinew to win it," it says.
"In wars from the Falklands to Iraq, the prime minister formed a special war cabinet. Why not now? Why not a minister for Afghanistan?"
Mr Clegg has already signalled the end of the cross-party consensus on Afghanistan in the UK, although he has stopped short of calling for a withdrawal of British troops or a timetable for withdrawal.
He and Lord Ashdown widen their criticisms of the conduct of the war to include Nato and the US.
They say there is a lack of co-ordination and a sense of drift coming from the Obama administration.
The article says: "The central failure is the absence of any clear international strategy.
"The British think Afghanistan is Helmand, the Canadians think it's Kandahar, the Dutch think it's Uruzgan, the Germans think it's the North and the Americans, until recently at least, thought it was bombing from B52s.
"Gordon Brown and his European allies have called for an international conference to review progress.
"This will be a waste of time if it does not produce the single, united international strategy that has so far been so disastrously lacking.
"Nato, too, has to wake up to the fact that it faces a catastrophic failure with very wide consequences for its own future, unless it can start working like an integrated military alliance, rather than a hotch potch of the committed and the half hearted."
The two men call for a new military strategy in Afghanistan and for a government of national unity.
They say the war is not quite a "lost cause", but add that "the clock is ticking. This is our last chance to turn things round".