By all accounts, the U.S. (and allies in the U.K. and France) appears to be marching ever closer to war with Syria in the form of (at least for now) a 2- or 3-day strike on key Syrian infrastructure with the aim of hobbling Syrian President Assad, rather than removing him.
There are several developments today, which we've rounded up here, including more reports of intelligence officials in various countries confirming the use of chemical weapons, and the fact that the U.K. intends to bring a resolution authorizing a strike to the U.N.
Meanwhile, from Reuters, this is a useful map to keep as a reference.