The Office of the Director of National Intelligence concluded in a report earlier this month that it is "very unlikely" a foreign adversary is responsible for the symptoms, attributing them instead to "preexisting conditions, conventional illnesses, and environmental factors."
Tourists ride classic convertible cars on the Malecon beside the United States Embassy in Havana, Cuba, Oct. 3, 2017. (AP Photo/Desmond Boylan, File)
Despite that conclusion, the Department of Defense is continuing their research into whether a weapon system could have caused the health incidents.
'HAVANA SYNDROME' NOT LIKELY CAUSED BY MICROWAVES OR OTHER FORMS OF DIRECTED ENERGY: CIA
That research should not include testing on live animals, which is not only "cruel and wasteful" but also "futile," PETA science policy adviser Maggie Wiśniewska wrote in a letter to the Pentagon on Monday.
"We again urge you to renew the ban on weapon-wounding tests on dogs, cats, marine animals, and nonhuman primates," Wiśniewska wrote in the letter.
"Such a prohibition should apply to but not be limited to the following: an apparent military plan to expose monkeys to pulsed microwave radiation in a misguided attempt to determine human brain effected associated with an acquired neurosensory syndrome, commonly referred to as ‘Havana syndrome.’"
People wait in line to enter the U.S. embassy in Havana, Cuba, on Jan. 4, 2023. (Reuters/Alexandre Meneghini )
Politico first reported last week that the U.S. Army gave a $750,000 research grant to Wayne State University to study whether ferrets exhibit similar symptoms to "Havana syndrome" when they are exposed to radio frequency waves.
Wiśniewska went on to argue that animal testing is counterproductive because many of the results don't translate to humans, writing that other more effective methods are available.
The Pentagon did not immediately respond to a request for comment on Thursday evening.