U.S. Navy warships are in position, ready to evacuate the U.S. embassy in Yemen, if needed.

The USS Iwo Jima and USS Fort McHenry have moved into the Red Sea, although no tasking orders have been given yet.

The move comes as Iranian-backed Shiite Houthi rebels shelled the presidential palace earlier, firing on residents. A top military official warned that a coup is underway.

Officials confirm that an embassy vehicle was fired on today, but no U.S. personnel was injured.

The U.S. embassy is currently open.

Watch Jennifer Griffin's report above.