F.B.I. Sharpens Scrutiny of Syrians in U.S.

"Senior national security officials at F.B.I. headquarters in Washington have told the bureau’s field offices in recent days to follow up with sources who have ties to Syrians in an attempt to find talk or evidence of a retaliatory strike, the officials said. And Syrians implicated in continuing investigations will be put under even closer scrutiny, the officials said."