John Kerry has just publicly announced what the U.S.A. was implicitly doing over a year and a half. Consider this. Once the American "red line," applied to the use of chemical weapons, was held back due to the fear of a change in regime and of worsening Syria's situation, Washington gave in to Tehran and Moscow by keeping Assad. Cunningly, he covenanted the delivery of a chemical arsenal as an exchange for the unofficial commitment to fight the rise of Islamic State, which was convenient for everyone. For the U.S.A., because after Iraq, Afghanistan and Libya, it had no room for another disaster associated with a military intervention. For Moscow, because it could maintain a strategic ally and access to the Mediterranean. For Tehran, because it couldn't drop a regional Shiite ally, crucial in the Sunni influence geography of Saudi Arabia and Turkey and also because that gave it weight in negotiations with the U.S.A. on the nuclear issue.

The imprisonment of the Levant by the Islamic State group — bound hand and foot in Libya, Nigeria, Egypt, Lebanon, Jordan and Yemen — did the rest. For Obama, air strikes are no longer enough. It is necessary to regain positions with boots on the ground. These boots are Iraqi and Iranian in Iraq and have to be Syrian and Iranian in Syria. This concession to Tehran still means another thing: Negotiations on the nuclear issue are going well for Iran. Timing helps reasoning. Washington is not going to give up on direct negotiations with Tehran nor has it given in to pressure from Netanyahu. The anti-Islamic State group front in Iraq is going better and needs a similar front in Syria. No opposition group to Assad has proven able to defeat the Islamic State group, and Shiites, Christians and Syrian Druze fear that Assad might lose. All this is summarized in these terms: The U.S.A. has never known what to do in Syria. But better late, than never.