The State Department on Thursday issued an extraordinary advisory urging Americans not to travel overseas and to return to the United States if they can, a move that comes amid concerns about the coronavirus pandemic.

The Level 4 travel advisory for all international travel appears to be unprecedented and is the most severe such warning issued by the department. It urges American citizens who live abroad or otherwise cannot reach the U.S. to essentially stay where they are and avoid crossing international boundaries. POLITICO first reported the plans for the advisory earlier Thursday.

Numerous U.S. citizens are already in limbo abroad, and the new guidance threatens to stir further anxiety among travelers. U.S. lawmakers have raised questions about the State Department’s…