A day after Secretary of State John Kerry called last week's alleged chemical attack on Syrian civilians a "moral obscenity," Syrian foreign minister Walid al-Moallem challenged the U.S. to provide evidence of chemical warfare, and said the country will defend itself "using all means available" in the event of a U.S. strike.

Such an attack seems likelier than ever now that the Obama administration has ordered the release of a report justifying a strike in the absence of U.N. support, as Taylor Berman writes below. The strike would likely involve cruise missiles fired at Syrian military installations, with the aim of punishing or ousting the regime of President Bashar al Assad. "Surgical strikes" of this nature would likely not put any U.S. troops in harm's way—but could also be among the least effective measures at ending or stopping Assad's use of chemical weapons.

Though the U.S. has, with significant evidence, essentially decided that the hundreds of civilians who died in a Damascus suburb last week were killed by Assad's chemical weapons, the U.N. hasn't been able to confirm—because the team of inspectors sent to the site has been turned back by sniper fire, and is now being delayed by a day to improve its chances of safe passage.

If the U.S. decided to go ahead with a strike without U.N. support (China and Russia, both on the security council, are still allied with Assad), it would likely be joined by the U.K., whose parliament was recalled today for "urgent discussion" on Syria, France, Turkey, Saudia Arabia, the United Arab Emirates and Qatar.