The United Arab Emirates said Tuesday that it was pulling out its remaining forces in Yemen, after Saudi Arabia bombed the war-torn country’s port city of Mukalla following accusations that two ships from the UAE had delivered weapons and combat vehicles to separatist forces.

Saudi Arabia has launched an air strike on a Yemeni port, targeting what it says were shipments of weapons and combat vehicles from the United Arab Emirates destined for southern separatist forces.

The attack signals a new escalation in tensions between the kingdom and the separatist forces of the Southern Transitional Council, which is backed by the Emirates.