The now breached compound that previously served as America's embassy, however, hasn't been active for years since the 2015 war started, when official State Dept. operations for Yemen moved to neighboring Saudi Arabia. 

But crucially, the Houthis have reportedly captured an unspecified number of local Yemenis who had staffed the prior US embassy in Sanaa, AFP news agency reports. While by the end of this week most of the detainees have been reported released, a number of employees of the embassy continue to be held hostage.

The US State Dept. is calling for their immediate release, in a scenario which parallels the August US troop withdrawal from Afghanistan, which left stranded many thousands of locals who previously worked under the US as the Pentagon hastily evacuated Kabul airport.

"We are concerned that Yemeni staff of the US Embassy in Sanaa continue to be detained without explanation and we call for their immediate release," a US official said in a Thursday statement. Washington is urging that the Houthis must "immediately vacate" the compound and return all seized property, the AFP writes.