The US charged former Cuban President Raúl Castro with murder, sharply escalating a standoff with Havana as the Trump administration attempts to force change on the island after nearly seven decades of communist rule.

Acting Attorney General Todd Blanche announced the move against Castro on Wednesday in Miami. The charges are related to the February 1996 downing by Cuba of two civilian aircraft operated by the Florida-based exile group Brothers to the Rescue.

The Cessnas were shot down outside Cuban airspace, killing four, according to an International Civil Aviation Organization investigation. The incident, which occurred while the 94-year-old revolutionary leader was defense minister, immediately became a highly sensitive diplomatic flashpoint and has been source of tension for the past three decades.

“For the first time in nearly 70 years, senior leadership of the Cuban regime has been charged in this country, in the United States of America, for acts of violence resulting in the deaths of American citizens,” Blanche said.