Updated

Cuban President Raul Castro stepped in personally earlier this year to deny his government was responsible after the United States demanded answers about American diplomats harmed in Havana.

U.S. officials say Castro sought out the top American diplomat in Havana for a rare face-to-face conversation. They say Castro relayed that he was just as befuddled about what was happening. The officials weren't authorized to discuss the meeting publicly and demanded anonymity.

Castro's reaction was surprising to U.S. officials. They say they would have expected Castro would react defensively or refuse to cooperate with the investigation.

The U.S. has said at least 21 diplomats suffered damage including permanent hearing loss and concussions. Canadian diplomats were also affected. A U.S. investigation has reached no conclusion about a device or a culprit.