The Trump administration is now calling those mysterious health ailments in Cuba "attacks" rather than merely incidents.

The State Department is warning Americans to stay away from Cuba as it orders home more than half its diplomatic corps.

Who is behind the attacks remains unknown to U.S. officials.

At least 21 diplomats and family members have been affected. The department says symptoms include hearing loss, dizziness, headache, fatigue, cognitive issues and difficulty sleeping.

Officials say that the U.S. Embassy in Cuba will stop processing visas for prospective Cuban travelers to the United States indefinitely.

Initially some futuristic "sonic attack" was suspected, but the picture remains muddy. The FBI and other agencies that searched homes and hotels where incidents occurred found no devices.