A missile was on Saturday fired on the headquarters of the U.S. embassy in the Yemeni capital Sanaa, a security source said.The attack had, however, caused no human casualties, the source, who requested anonymity, told Anadolu Agency.He said it was still unknown who stood behind the attack.AA could not immediately obtain comments on the attack from US embassy officials. Yemeni authorities have not issued an official statement either.The attack comes only one week after Shiite Houthis had controlled the Yemeni capital and signed a political partnership agreement with the presidency.Sanaa fell in the hands of the Houthis after almost three weeks of protests and confrontations with army troops and policemen.On Sunday, Yemeni President Abd Rabbuh Mansour Hadi-faced with massive pro-Houthi demonstrations that paralyzed the capital - signed a deal with the Houthi leadership aimed at ending the weeks-long political standoff.The deal calls for the formation of a new government; the appointment of a nonpartisan prime minister; and the appointment of a Houthi adviser to the president.Yemen has been dogged by political turmoil since the 2012 ouster of longtime ruler Ali Abdullah Saleh.