United States officials are not entirely confident they know who is behind the airstrikes being reported against Islamic State of Iraq and Syria forces in western Iraq. From ABC News:
According to the U.S. official, the United States has “pretty good information that the Syrians are behind the fighter aircraft bombing in western Al Anbar,” a province in Iraq that includes the Syrian border. The official said the United States is still trying to gather more information that Syria was behind the strikes...
A U.S. official also said it was not clear whether the Iraqi government requested or authorized Syrian air strikes in Iraqi territory.
The Wall Street Journal reported confidently this morning that Syrian planes carried out the attacks—which killed at least 50 people—and it seems improbable that any other group would have the motive or the means to strike in that area. But the WSJ also wrote that U.S. officials "weren't able to confirm" Syria's involvement.
The level of uncertainty about the events, and especially the Iraqis' role therein, is particularly striking given that U.S. military personnel in Baghdad are actively advising the Iraqi government in its war against ISIS.