After nearly five years, someone and something is still causing serious injury to U.S. officials abroad. The source of “Havana syndrome,” first detected in Cuba in late 2016, has not been identified nor attributed. The attacks — and they do seem to be deliberate attacks — now total more than 200 cases.

After then-President Donald Trump’s chaotic handling of the crisis, the Biden administration has intensified the search for the source and attempted to break down the silos that hampered internal government cooperation. The State Department’s top official overseeing the issue, Pamela Spratlen, has stepped down after six months on the job, following friction with some of the victims. The department says her permitted time serving as a retiree was up. Meanwhile, Congress just passed legislation to help victims. But the cause of the illnesses remains a mystery. If the source is “directed, pulsed radio frequency” energy, as some research suggests, who is aiming it at U.S. diplomats and intelligence officers? How have the perpetrators managed to conceal sneak attacks on U.S. officials around the world? They have not made any demands. Are they trying to disrupt the work of spies and diplomats to create chaos and uncertainty? Or worse?

The victims have reported suffering headaches, dizziness, blurred vision and memory loss after hearing strange noises and feeling odd sensations. The injuries are real and have serious and lasting consequences. The latest cases involve dozens of U.S. personnel in Vienna, as well as some children. More cases have been reported in Vienna than in any other city but Havana. John Hudson and Shane Harris of The Post report that the CIA has recalled its station chief in Vienna for insufficient attention to the problem. Some offices within the U.S. mission were shut down, impairing embassy functions.

On top of this, when CIA Director William J. Burns was in India recently, a member of his team reported being hit and required medical care, CNN reported. When Vice President Harris was heading to Vietnam in late August, her arrival was delayed several hours because several U.S. officials on the ground suffered symptoms and two had to be evacuated for medical attention.

We’re told there is a great deal of heterogeneity in the cases. There might be more than one mechanism behind the various incidents, too. Still, it is frustrating that Americans are being sent abroad on vital military, diplomatic or intelligence missions facing unknown peril from invisible sources and that the U.S. government has so far been unable, with all its capabilities, to pinpoint what is causing this danger.

Eventually, the culprits must be found and held to account. But first, the injurious emissions have to be stopped. The health and well-being of U.S. officials abroad demand no less. National security depends on those officials to be the eyes and ears of the United States. It is unacceptable that someone is trying to punch them out, and is getting away with it.