DEVELOPING: The U.S. has ordered the expulsion of 15 Cuban diplomats from their embassy in Washington following mysterious attacks on American officials in Havana.

U.S. officials said the diplomats must leave the country within seven days. While the move is described as an “expulsion,” the U.S. isn’t declaring them “persona non grata” — a designation that would prevent them from ever returning, according to a State Department official.

Secretary of State Rex Tillerson said Tuesday the decision was made because Cuba failed to protect diplomats on its soil — without directly blaming Cuba for the attacks on Americans in Havana.

“The decision was made due to Cuba’s failure to take appropriate steps to protect our diplomats in accordance with its obligations under the Vienna Convention,” Tillerson said in a statement.