WASHINGTON — America has returned to war, of a sort, in Iraq with airstrikes that have intensified in recent days against Islamic State militants. But details about the execution of this limited campaign, which so far includes no reported U.S. ground combat, are thin.

Some questions and answers about the mission, which began Aug. 8:

Q. What U.S. forces are involved?

A. The specifics are hard to pin down in part because, as in any U.S. overseas conflict, many of the contributors work behind the scenes, sometimes in secret. We do know that the U.S. has about 750 military personnel in Iraq, not counting the 100 who have worked out of the U.S. Embassy in Baghdad since before this crisis began.

None of the 750 are engaged in ground combat, but that does not mean they are not at risk.