In October of last year, American diplomats in Cuba began to report to their superiors of strange noises and inexplicable headaches. The phenomenon was not localized to one single location, yet only affected the U.S. and Canadian staff working at the embassies. This seemed too specific to be labeled as coincidence.

Now, over 10 months later, the same diplomats are experiencing equally strange symptoms including nausea, nose bleeds and brain damage, leading the Federal Bureau of Investigation and other U.S. officials to speculate that these diplomats experienced a deliberate attack.

So far, 21 employees of the United States Embassy in Havana were targeted by what has been described as an “acoustic” assault. Whether they were working within the embassy offices themselves or sleeping in their own bed, all involved described hearing a high-pitched blaring and grinding noise. Medical experts were called upon to investigate and concluded that the source of the ultra-frequency sound waves may have originated from a “covert sonic device.”

The method of the attack, and its varying symptoms, has the fbi puzzled and the U.S. pointing the finger at Cuba.

The Cuban government has strongly denied any involvement. “Cuba has never, nor would it ever, allow that the Cuban territory be used for any action against accredited diplomatic agents or their families, without exception,” read a statement from Havana.

However, the strange attack bears close similarities to plans carried out against the West by Soviet spies during the cloak-and-dagger days of the Cold War. In the ’50s and ’60s, the American embassy in Russia was attacked with unusual microwave transmissions.

Cuba was an ally of the ussr for years, and kgb agents were known to have worked closely with the Cuban government. It is possible that the technology and tactics of the former Soviet Union are being turned against America once again.

In response to the attacks, the Trump administration is considering closing the recently reopened embassy. Earlier in September, U.S. Secretary of State Rex Tillerson revealed on cbs’s Face the Nation that the decision is currently under review, saying that the safety of American personnel made it a “very serious issue.” On September 29, the State Department announced that, for the time being, it will scale back the staff in Cuba.

The full extent of this action’s repercussions are uncertain. Nevertheless, political turmoil between the United States and Cuba endangers the whole region.

Trumpet editor in chief Gerald Flurry has warned of Cuba’s connection with terrorism. In the March 2015 Trumpet issue, he wrote concerning the original deal that tried to bring the two nations together and to legitimize what is still a dictatorship (emphasis added):

This is a bad deal for the Cubans. Was it good for the people of the United States? Under the Castro regime, Cuba has acted as one of the Western Hemisphere’s major sponsors of terrorism and drug trafficking. Legitimizing it is a victory for those who want to see America fall. Giving in to that Communist regime emboldens America’s enemies.

Cuba has been a state sponsor of terrorism for decades. In the late ’70s and early ’80s it was known that Castro was arming and supporting rebels in American allied countries as well as providing a safe haven for fugitives wanted in the United States. According to a 2011 State Department document, “it has remained opposed to the U.S.-led coalition prosecuting the war on global terrorism and has been actively critical of many associated U.S. policies and actions. On repeated occasions, for example, Cuba sent agents to U.S. missions around the world who provided false leads designed to subvert the post-September 11 investigation.”

Having this state supporter of terrorism so close to American soil poses a greater danger than people seem to believe. As the history of the Cuban Missile Crisis suggests, its potential to be directly involved or to abet a farther distant hostile power in an attack on the U.S. should not be underestimated.

For more on the danger posed to the U.S. by Cuba, read Mr. Flurry’s article “The Deadly Dangerous U.S.-Cuba Deal.”