U.S. State Department spokesperson, Jen Psaki expressed Thursday her deep concern over the recent clashes between pro-Hadi troops and rebels at the Aden Airport and the Houthi air strikes on the presidential palace in Aden. "We're actively monitoring the situation. We're concerned about actions that could increase tension in Yemen and lead to further destabilization," Psaki said. She called on all Yemeni factions to de-escalate the situation, and refrain from violence, asserting that the state department has been in contact with Yemen's President Abd Rabbuh Mansour Hadi recently. Intensive armed clashes occurred early Thursday between military forces loyal to President Hadi and forces loyal to former president Ali Abdallah Saleh and other Houthi fighters at the Aden International Airport. The pro-Hadi forces led by Defense Minister, Mahmoud Subaihi managed to regain control of the airport. Hadi has been attempting to dominate Aden, ever since he fled to the southern province late February following the seizure of the capital Sana'a by Houthi rebels.