The United Arab Emirates said on Tuesday it was pulling its remaining forces out of Yemen after Saudi Arabia backed a call for UAE forces to leave within 24 hours, deepening a crisis between the two Gulf powers and oil producers.

Hours earlier, Saudi-led coalition forces had attacked the southern Yemeni port of Mukalla. The airstrike on what Riyadh said was a UAE-linked weapons shipment was the most significant escalation to date in a widening rift between the two Gulf monarchies.

In Washington, the U.S. State Department said Secretary of State Marco Rubio spoke ?with the Saudi and UAE foreign ministers about tensions in Yemen and other issues affecting security in the Middle East.