WASHINGTON — As American authorities search for answers into mysterious “health attacks” that began two years ago in Havana, U.S. and Cuban officials were renewing efforts to determine the method and motive behind incidents that have left some diplomats with brain injuries.

A meeting Thursday between U.S. and Cuban officials was intended to try to help determine the method and motive behind those mysterious incidents that began nearly two years ago and have affected about two dozen people, including some diagnosed with brain damage.

A flurry of reports has suggesting investigators have narrowed their suspicions as to the cause and culprit.

Cuba’s foreign ministry said nine members of the scientific team it assembled to look into the incidents met with members of Congress and the National Academy of Sciences before the talks at the State Department.

The Cuban Embassy in Washington said the team is proposing “a dispassionate examination of health reports of U.S. diplomats in Cuba according to the rules of science.”

The planned meeting is “part of our ongoing effort to investigate and better understand the health conditions of our diplomats,” the State Department said.

It said the Cuban delegation would “receive a general medical briefing about the injuries experienced by U.S. personnel who served in Havana.”

The department has played down or denied reports that investigators have focused on a microwave device as the source of the attacks and that Russia is the leading suspect.

The reports have raised protests from Cuba, which does not dispute the symptoms but insists there is no evidence to support any assertion that they were caused by premeditated attacks on its soil.

Twenty-five U.S. Embassy workers in Cuba, as well as one at the U.S. consulate in Guangzhou, China, have been affected by mysterious health incidents that began in the fall of 2016. The range of symptoms and diagnoses includes mild traumatic brain injury, also known as concussion.

The last case from Havana was confirmed in June. The U.S. said two embassy staffers were affected in a single occurrence in late May in a diplomatic residence at which both officers were present. Those were the first confirmed cases in Havana since August 2017.

One U.S. official said Thursday’s meeting was organized after Cuba complained that Washington has withheld important details about the affected Americans’ medical conditions. The official was not authorized to discuss the matter publicly and spoke on condition of anonymity.

In congressional testimony last week, State Department medical personnel suggested they had shared more information with China about the incident in Guangzhou than they had with the Cubans about what has happened in Havana.

In two classified briefings with congressional aides and lawmakers last week, the officials repeated that they had not come to any conclusions about what caused the injuries or who might be responsible for them, according to officials familiar with the meetings.

Initial speculation had centered on some type of sonic attack, owing to strange sounds heard by those affected. But an interim FBI report in January found no evidence that sound waves could have caused the damage