"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.
The Shiite Muslim militia that has grabbed power in Sanaa warned Tuesday against any attempts to "destabilise" 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 marginalised 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.