In the U.K., any sign of British military getting bogged down in a long and costly engagement could see the public turn on Mr. Cameron, in the way many turned on former Prime Minister Tony Blair as the Iraq war became more deadly and costly.
For now, however, Monsieur Sarkozy and Mr Cameron are reaping the benefits of their pro-war campaign.
France's opposition Socialist Party, which rarely has any words of praise for Mr. Sarkozy, lauded his Libyan stance.
"If the international community had not reacted, it would have meant a free hand for all dictators," French Socialist Jean-Marc Ayrault told reporters, after a meeting during which members of Mr. Sarkozy's government briefed lawmakers on its Libyan plans.
Mr. Sarkozy's boldest move in the international stand-off came last week when even to the surprise of French diplomats he recognized Libya's opposition movement as the country's only true representative. That decision marked a sharp change in France's diplomacy in the Arab world, a region where Paris has traditionally supported stability more than change.
The move also helped France draw a line under a string of embarrassments that had muddied its diplomatic efforts since the start of uprisings in Tunisia, Egypt and other Arab nations, analysts say.
France has "failed to seize the sense of despair and the suffering of Tunisia's population," Mr. Sarkozy acknowledged in late January.
Mr. Cameron's biggest problem though is that the UK media and public will likely soon focus on the fact he is offering the services of a military whose budget last October he said he would cut 7.5% to help reduce record British debt. The cuts will hit aircraft, ships and artillery, and will leave the UK with no aircraft carrier capability in the coming decade.
Some military officers have already expressed reservations to the UK government that committing assets in Libya, alongside those in Afghanistan, will take away the U.K.'s ability to react if other countries need military interventions, including those that have greater strategic interest for the UK such as Iran and Bahrain.
Roots of Strategy: The 5 Greatest Military Classics of All Time (Bk. 1)
