"On February 11, 2015, due to the deteriorating security situation in Sanaa, the Department of State suspended embassy operations and US Embassy Sanaa American staff were relocated out of the country," a State Department travel warning said.
"All consular services, routine and/or emergency, have been suspended until further notice," it added.
In addition, US nationals were urged to leave Yemen, it said.
"The Department urges US citizens to defer travel to Yemen and those US citizens currently living in Yemen to depart," it stressed citing: "the high security threat level in Yemen due to terrorist activities and civil unrest."
The Shiite Muslim militia that has grabbed power in Sanaa warned Tuesday against any attempts to "destabilize" Yemen as the UN brokered a second day of talks aimed at resolving the crisis.
The country has never managed to achieve stability since longtime president Ali Abdullah Saleh stepped down in early 2012 after a bloody year-long popular uprising.
This includes battling an Al-Qaeda insurgency and facing a separatist movement in the formerly independent south.
Matters worsened in September when the Huthi militia, fearful of being marginalized by a proposed new constitution, seized control of the capital and began pushing southward into Sunni Muslim areas.
UN envoy Jamal Benomar has warned that Yemen is at a "crossroads", and urged political leaders to "take up their responsibilities and achieve consensus" as he battles for a negotiated solution.
The United States pressed for progress on that front.
"We reiterate the call of the United Nations Security Council for immediate release of President Hadi, Prime Minister Bahah, and members of the Yemeni cabinet. An inclusive political process cannot resume with members of the country’s leadership under house arrest," State Department spokeswoman Jen Psaki said in a statement.
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