The State Department announced Sunday evening that if Russia invades Ukraine, the U.S. government won’t be able to get Americans trapped behind enemy lines out of the country.

“Given that the President has said military action by Russia could come at any time. The U.S. government will not be in a position to evacuate U.S. citizens. So U.S. citizens, currently present in Ukraine should plan accordingly,” a State Department official said on a call with reporters, advising Americans to book commercial flights as soon as possible.