SANAA - The United States is closing its embassy in Yemen, the Arabian peninsula state that is a front line in Washington's war against al-Qaida, embassy employees and US officials said on Tuesday.US officials in Washington confirmed the embassy would close because of the unpredictable security situation in a country where a rebel group has seized control of the capital, Sanaa. State Department spokeswoman Jen Psaki declined comment. But she noted that the embassy staff had been gradually reduced and said the safety of the personnel was a top priority. "We take steps in order to make sure we do everything we can to protect that," she told a regular briefing.Last month, Iran-backed Shi'ite Muslim Houthi fighters, who had captured the capital in September, seized the presidential palace, driving President Abd-Rabbu Mansour Hadi and his government to resign.After years of crisis, Yemen now risks descending into a full-blown civil war pitting regional, political, tribal and sectarian rivals against each other in a nation that shares a long border with top global oil exporter Saudi Arabia.Yemen is home to al-Qaida in the Arabian Peninsula, one of the most active branches of the global Sunni Islamist group.The United States has long used drones to attack the militants, a strategy critics say has failed to make a decisive difference and has stoked anti-US sentiment.One US official said a contingent of around 100 Marines was helping protect the US embassy in Yemen. Another official said a Navy amphibious assault ship, the USS Iwo Jima, was in the Red Sea off Yemen's coast and would be available to help with the evacuation of embassy staff, if requested by the State Department.