U.S. embassies and military bases across the Middle East are on high alert, as fears grow about and Israeli strike on Iran.

The U.S.’ moves to evacuate some State Department personnel and military families from the Middle East are seen by experts as a potential sign of a U.S. or Israeli strike against Iran’s nuclear program — or, at least, a signal to Iran that the U.S. is prepared for such action, ahead of another round of nuclear talks with Tehran.

The move comes after the Iranian defense minister warned that Tehran would target U.S. bases in the area if tensions escalated.