The Associated Press released a report on October 3rd that described a series of unusual attacks on United States embassy personnel in Havana, Cuba. According to the report, "the Trump administration largely has described the 21 victims as U.S. embassy personnel or 'members of the diplomatic community.'"

Many of the victims are members of the intelligence community, leading some to speculate that the mysterious attacks may involve espionage on some level.

"Of the 21 confirmed cases, American spies suffered some of the most acute damage, including brain injury and hearing loss that has not healed, said several U.S. officials who weren’t authorized to speak publicly on the investigation and demanded anonymity," said the AP report.

Victims describe a sudden wave of nausea, dizziness, and headaches that follow strange sounds that they compared to loud crickets or screeching metal. U.S. officials believe that the attacks may be targeted, and are investigating the possibility that some sort of sonic weapon could have been used.

FBI investigators have been unable to find any evidence of a device capable of inflicting the wounds suffered by embassy personnel. Investigators have created a map detailing specific areas of Cuba’s capital where attacks have occurred in order to better identify patterns, and three geographic clusters of attacks exist, which cover the homes of U.S. diplomats and several hotels, including the historic Hotel Capri.

Victims have been treated for ear complaints, hearing loss, dizziness, tinnitus, balance problems, visual complaints, headaches, fatigue, cognitive issues and difficulty sleeping, a senior U.S. official told CNN.

So far, as many as 50 attacks are believed to have been carried out.

Cuba vehemently denied any involvement or knowledge of the attacks, and some U.S. officials believe they may be telling the truth.

"When President Raul Castro denied any culpability in February, he did so on the sidelines a meeting in Havana with five visiting U.S. members of Congress," said the AP. "The U.S. had raised complaints about the attacks to Cuba just days earlier through diplomatic channels."

The visiting lawmakers were wholly ignorant of the attacks taking place, however, nor were they aware that Castro had used the occasion to express his own concern and willingness to help privately to top U.S. diplomat Jeff DeLaurentis.

Doubt over Cuba's involvement in the attacks has led to speculation about whether or not a third party state might be involved, such as Russia, China, or North Korea. The motive cited for such an attack would be to worsen relations between the United States and Cuba.

Regardless of the cause, the U.S. government has issued a travel warning to Americans that deems Havana's hotels unsafe for visitors, ordered nonessential staff and the families of employees out of Cuba, and has correspondingly expelled 15 Cuban diplomats from the U.S.