The latest study about what happened to U.S. diplomats in Cuba does not solve the case but does require that it be pursued. An investigation by scientists reveals that several dozen diplomats stationed in Havana suffered brain trauma when compared with a similar sample of healthy adults. The United States must continue to demand accountability for whoever did this, and the first step is to find out who, and why.

The new research, published in the medical journal JAMA, looked at imagery of brain scans of 40 people who complained of symptoms such as hearing loss, dizziness, tinnitus, visual difficulties, headaches, fatigue, as well as cognitive, balance and sleeping difficulties after serving for some time at the U.S. Embassy in Havana. The scans of 23 men and 17 women were made when they returned to the United States between August 2017 and June 2018. The study, using advanced brain magnetic resonance imaging techniques, showed “significant” differences in the brain matter of the diplomats compared with the control group. In particular, it found the diplomats had smaller volumes of gray matter in the brain that makes up the organs that control vision, hearing and movement, and smaller amounts of white matter, the wiring that connects the cells and organs. The study found no differences between the diplomats and the control group in the executive-control network for thinking and planning.

The authors of the study acknowledge it had limitations: a small sample, a control group that was not ideal, and the methods could not offer any clues about what external event caused the trauma. A fair amount of mystery still shrouds the whole episode. The FBI was brought in to investigate, but its findings are not known. There has been speculation the U.S. diplomats, and some from Canada, were attacked by a weapon or device such as a microwave beam or sonic waves, but there is no confirmation. The illnesses appear to have come after President Barack Obama’s initiative that led to restoration of diplomatic relations with Cuba in 2015. It might have been intended to sour the restart.

Fallout from the diplomats’ trauma has caused very real difficulty for the Cuban people. Personnel levels at the U.S. Embassy in Havana have been sharply curtailed, forcing Cubans to seek travel visas and other consular services in third countries.

The Cuban regime promised to investigate, came up empty-handed and has denied the diplomats were attacked. Foreign Minister Bruno Rodríguez declared of the latest research, “there isn’t the least evidence or scientific explanation supporting deliberate actions against diplomats” in Cuba, which remains “a safe, stable and friendly Island.”

It clearly was not safe for the diplomats who suffered brain trauma. Cuba has a pervasive security service. Surely it knows what really happened. Instead of urging everyone to look the other way, Cuba’s government should get to the bottom of this and make public the findings. The United States must demand no less.

— The Washington Post