The mysterious health attacks that U.S. diplomats in Cuba have suffered reportedly began shortly after President Trump won the election last November.

According to The Associated Press, the attacks began “within days” of Trump’s victory and hit spies working at the United States embassy in Havana.

{mosads}The State Department last week announced that it ordered approximately 60 percent of its staff and family members to leave the U.S. embassy in the country’s capital following the attacks. An official also said the U.S. would cease issuing visas in Havana for an indefinite period of time.

There have been 21 confirmed cases of diplomats suffering from the mysterious attacks, with symptoms including hearing loss and sleeping difficulties. The health attacks first came to public light in August.

U.S. investigators are still working to determine the cause of the symptoms.

The government in Cuba has denied responsibility for the attacks and has offered the FBI unprecedented access in the country as it conducts the investigation.

A State Department official last week said it has not ruled out the possibility that a third country may have been involved in the attacks.