The NATO leaders’ hope is that their still-limited military action can provoke someone in Tripoli to overthrow Kadafi. The regime is brittle, they say; its “brother leader” is no indomitable giant like Vietnam’s Ho Chi Minh. Libya watchers in the intelligence community say every week brings new reports of generals and other Kadafi loyalists who are on the verge of defecting.

Except most of them haven’t. And so, in addition to the best-case scenario of a palace coup, U.S. officials now talk increasingly of a longer-term scenario: a war of attrition…

If time is not on Kadafi’s side, it won’t always be on the side of Obama, Cameron and Sarkozy either.

Their publics are already unhappy about the cost of another military commitment. NATO’s stature won’t be enhanced by a stalemate at the hands of one of the Arab world’s least impressive armies. The war has caused friction inside the alliance as Europeans pressed for more U.S. involvement and the Obama administration sought less. But having committed themselves to overthrowing Kadafi, Obama, Cameron and Sarkozy can’t back off now.