Federal prosecutors in the United States could soon announce a possible criminal indictment against former Cuban president Raúl Castro, according to sources familiar with the matter.

The investigation is reportedly being handled by prosecutors in the Southern District of Florida and is focused on the 1996 downing of aircraft operated by Brothers to the Rescue, a Miami-based group that conducted missions related to Cuban refugees.

The humanitarian organization’s planes were shot down by Cuban fighter jets in an incident that heightened tensions between Washington and Cuba and drew international condemnation.

Reports of a potential indictment come as President Donald Trump has intensified his rhetoric toward Cuba in recent weeks.

Earlier this month, Trump suggested the United States could shift its focus toward Cuba following developments involving Iran, saying, “Cuba is going to be next,” and claiming the U.S. would be “taking over Cuba almost immediately.”

No formal charges against Castro had been announced as of Friday, and U.S. officials have not publicly commented on the status of the investigation.