The State Department believes some of its diplomats in Cuba fell victim to a covert device which caused significant hearing loss.
If accurate, it could be an unprecedented move.
The incident occurred in fall 2016 and forced some diplomats to return home to the U.S. from their tour of duty early.
An investigation determined that the device used was outside the range of human hearing, deployed either inside or outside the diplomatic residences.
Officials are also uncertain if the device used was some kind of weapon or another tool.
That said, officials told the Associated Press that it is not the first time American diplomats in Cuba have been harassed.
It may sound like science fiction, but the use of sound in warfare is not unheard of.
According to the Bible, the Israelites used their trumpets to destroy the walls of Jericho.
Ancient Mexican tribes were known to use the Aztec death whistle to strike fear in the hearts of their enemies.
More modern examples include the Nazi Germany's use of terrifying sirens on their planes and rockets, and the U.S. using eerie voodoo sounds to haunt enemy soldiers in the Vietnam war.
Military and police forces across the globe additionally use non-lethal weapons like flashbang grenades to incapacitate targets.
Another popular tool is the LRAD, short for long range acoustic device. While capable of sending sound beams over great distances, the LRAD is meant to be heard, unlike the strange, inaudible device that is believed to have affected the diplomats.
Regardless of the science, harming diplomats is well beyond what is considered typical international relations.
"This really does step beyond what is considered normal for harassment," Dr. Vince Houghton, the curator and historian of the International Spy Museum in Washington, D.C., told Circa. "Harassment happens, but in most cases it doesn't reach the point where there's permanent injury."
Houghton noted that this example could have been a prank gone too far, or an unintended side effect from a beta test for a new technology.
"But most of the time you're not trying to maim somebody, mainly because what you do to somebody else can be done to your guys overseas," he said.
Houghton additionally mentioned there are some "unwritten rules" when it comes to how much nations can do in diplomacy and intelligence work overseas.
The idea of adversarial countries bumping one another's spies and diplomats off like in the movies is not the norm in real world spycraft.
There's some doubt surrounding the capabilities of sonic weapons, so a direct attack with an effectively silent sonic device would be groundbreaking in both science and diplomacy.
The Associated Press contributed to this report.