The State Department confirmed on Aug. 24 that at least 16 U.S. government employees were affected by alleged sonic weapons attacks in Cuba. State Department spokesperson Heather Nauert said in a video that the individuals showed symptoms and are being treated in the United States and Cuba. She said “we take this situation extremely seriously.”

The update corroborates news stories stating that in late 2016, diplomats in Cuba began showing symptoms inducing nausea, headaches, and balance disorders. CBS News reported on Aug. 23 that U.S. and Canadian diplomats in Cuba were diagnosed with mild traumatic brain injury and central nervous damage after alleged sonic weapon attacks on their homes.

While the Cuban government has denied any involvement in the attacks, according to ZeroHedge,  Secretary of State Rex Tillerson said, “We hold the Cuban authorities responsible for finding out who is carrying out these health attacks.”

According to Rick Fisher, senior fellow with the International Assessment and Strategy Center, the incident follows a long-running trend.

“My first reaction was that it’s similar to what the Soviets were doing to our diplomats in the early-to-mid 1980s,” he said.

He notes that at the time the Soviets were using microwave weapons to target diplomats, and that it was possible “they might have shared data or even the weapons technology with the Cubans.”

The timing of the attacks is important, he said. They began in late 2016, at a time when former president Barack Obama was ending the U.S. trade embargo on Cuba and the “wet foot, dry foot” policy that formerly granted U.S. citizenship to Cubans who set foot on the United States.

Fisher noted that while these actions would normally be interpreted as positive for diplomatic relations between two countries, history has shown this is not the case when dealing with Marxist-Leninist regimes like Cuba.

“This is typical of Marxist authoritarian regimes,” he said. “Usually when the U.S. reaches out its hands in friendship without any expectation for in-kind reciprocation, we get our hand bitten.”

“They don’t want peace with the United States. Peace with the United States helps relax their own dictatorial control of their own society,” he said.

Based on this background, he said, it would make sense a communist regime would view otherwise friendly gestures as “a gesture of hostility, and came up with the reaction of directly damaging American diplomats. That’s how a Leninist would respond to American peaceful entreaties, and at a minimum, Cuba is controlled by Leninists.”

All such regimes in the world—including the North Korean communists and the Chinese Communist Party—”are all engaged in significant anti-American activities,” Fisher said. “They are either from nuclear to conventional, to harsh political challenges. Maybe the Cubans have decided they have to join their plans and also be antagonistic towards the United States”

This view of Leninist hostility to the United States also makes sense from the viewpoint of longstanding relations between the two countries.

“Both sides have been intensely targeting each other for espionage and counter-espionage operations since the 1960s,” Fisher said. “And the current exercise against the Americans could be as much a reflection of internal tensions in the Cuban leadership over whether to pursue better, or to create worse, relationships with the Americans.”

While sonic weapons may sound strange, Fisher noted they have a long history. “The Germans invented them around World War II to attack infantry units,” he said. “These are probably much more superior designs.”

Such weapons, he said, are not necessarily audible. They use sound waves as a weapon, and when focused and digitally enhanced, the sound waves “can be turned into a destructive energy force that could conceivably damage organs.”