Federal authorities are intensifying counterterrorism monitoring across the United States amid concerns Iran or its sympathizers could attempt retaliation following U.S.-backed strikes on Iranian leadership, according to administration officials and a former FBI counterterrorism supervisor.

Secretary of War Pete Hegseth, addressing the strikes on Iran for the first time since they took place just after midnight on Friday, said the Trump administration is watching closely for any signs of sleeper-cell activity or inspired violence but emphasized that agencies are already positioned to respond.