Trump blames Cuba for diplomat attacks

President Donald Trump says he believes Havana responsible for a series of incidents Washington thinks hurt at least 22 US diplomats over a period of months in Cuba.

"I do believe Cuba is responsible," Trump told reporters at an impromptu White House news conference on Monday.

"I do believe that. And it's a very unusual attack, as you know. But I do believe Cuba is responsible."

The United States has not formally concluded Cuba carried out the attacks, some of which involved high-pitched sounds, but it has said Havana is responsible for ensuring the safety and security of US diplomatic personnel and failed to do so.

At least 22 diplomatic personnel were affected by the unexplained incidents, which have caused hearing loss, dizziness, fatigue and cognitive issues. Some private US travellers also have been affected.