WASHINGTON (Reuters) - President Donald Trump said on Monday that he believes Havana is responsible for a series of incidents that Washington thinks hurt at least 22 U.S. diplomats over a period of months in Cuba, prompting Washington to scale back its presence there.  I do believe Cuba is responsible,  Trump told reporters at an impromptu news conference in the White House Rose Garden.  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 U.S. 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 U.S. travelers also have been affected. 