Former Cuban President Raul Castro has been indicted in the United States on murder charges, court records showed on Wednesday, in a major escalation in Washington’s pressure campaign against the island’s communist government.

Cuba’s foreign ministry did not immediately respond to a request for comment. Castro, 94, last appeared in public in Cuba earlier this month, and there is no evidence that he has since left the island or that the government would allow him to be extradited.

The indictment comes as U.S. President Donald Trump has pushed for a regime change in Cuba, where Castro’s communists have been in charge since his late brother Fidel Castro led a revolution in 1959.

The details of the charges were not immediately available. A U.S. Justice Department official told Reuters last week on the condition of anonymity that the charges against him were expected to be based on a 1996 incident in which Cuban jets shot down planes operated by a group of Cuban exiles.