Cuban Foreign Minister Bruno Rodriguez addressed the United Nations General Assembly on Friday. He encouraged the United States to assist Cuba in investigating the mysterious cause of medical conditions affecting American Diplomats in Havana, Reuters reported. Rodriguez also urged the U.S. to avoid politicizing the problem only days after officials in Washington, D.C., said the U.S. is considering shutting down the embassy in Cuba.

Rodriguez informed the United Nations (U.N.) that top-level officials in Havana ordered an investigation into the underlying cause of the mysterious illnesses – which have the potential to create a rift between the former Cold War enemy countries.

U.S. contemplates closing embassy in Cuba following ‘health attacks’

Rex Tillerson, U.S. Secretary of State, described the medical-related problems as “health attacks,” the Chicago Tribune reported. The U.S. State Department, however, calls the symptoms “incidents.” Semantics aside, Tillerson stated on September 17 that the U.S. is contemplating closing the embassy in Havana, though it only recently reopened.

A government source from Cuba reportedly told Reuters, though, that the U.S. hasn’t provided the Cuban government with evidence of physical damage. The U.S. alleges illness symptoms include dizziness, nausea, and hearing loss are being experienced by U.S. diplomats and their family members.

The source further stated that no Cuban doctors have examined any of the people the U.S. claims have been harmed by an unknown cause. Cuba has denied involvement in the illnesses.

Cuba cannot find ‘causes or origin’ of diplomats’ health conditions

As a result of Cuba’s preliminary investigation into the genesis of the health problems, Rodriguez pointed out to the U.N.

that his country has "found no evidence whatsoever that could confirm the causes or the origin" of the incidents, the Tribune reported. Cuba’s investigation, as well as the investigation that U.S. commenced, is ongoing.

Rodriguez also told the U.N. that it is crucial for authorities in the U.S. to cooperate with Cuba so that the investigation into the mysterious cause of the alleged health problems can be determined.

“It would be unfortunate,” he stated, “if a matter of this nature is politicized,” Reuters relayed.

Number of ailing U.S. citizens in Cuba, with ties to embassy, stands at 21

The total number of U.S. citizens hit with an illness of undetermined etiology, now stands at 21, according to a U.S. State Department official last week. While some of the people with the health conditions returned to the U.S. for testing and treatment, others were tested in Cuba – by a full-time medical officer at the embassy, the official also noted.

In August, the U.S. government confirmed that officials were investigating the diplomats’ ailments, which reportedly started surfacing late in 2016. A Canadian official also said that several Canadians were affected by illnesses, which deepened the mystery, according to Reuters.

Theories on mystery cause of ailments from technology to covert sonic attack

There are various theories surrounding the mystery cause, which range from surveillance technology gone haywire to a type of acoustic weapon or, possibly, something that a third-party nation deployed. Iranian, North Korean, or Russian involvement is core to some theories but, as Reuters pointed out, most speculation flounders.

Investigations by the U.S., Canada, and Cuba haven’t produced answers to the cause, yet experts tend to be in agreement that it’s difficult to understand how covert attacks could have been conducted, Reuters reported. It is also hard for the experts to arrive at the potential motivation.

Audiologists have brought doubt into the realm of possibility and question whether there is any sonic weapon in existence that can covertly lead to the type of symptoms diplomats said they were experiencing.