WASHINGTON, United States, Monday October 2, 2017 – The United States Department of State has warned Americans not to travel to Cuba because of a series of sonic attacks on diplomats in recent months.

During the summer, at least 21 employees at the US Embassy in Havana were targeted in specific attacks. They reported a range of symptoms including hearing loss, dizziness, headaches, fatigue, cognitive issues and difficulty sleeping.

A sonic attack is the use of extremely high-power sound waves that can disrupt or destroy the eardrums of a target and cause severe pain or disorientation.

“Because our personnel’s safety is at risk, and we are unable to identify the source of the attacks, we believe US citizens may also be at risk and warn them not to travel to Cuba,” the State Department said.

Last Friday, it ordered the departure of nonessential US employees and their families. It said that until the Cuba government can assure the safety of US Government personnel in Cuba, the embassy will be reduced to emergency personnel so as to minimize the number of US Government personnel at risk of exposure. The remaining personnel will carry out core diplomatic and consular functions, including providing emergency assistance to US citizens in Cuba.

Routine visa operations were also suspended indefinitely, and short-term travel by US Government officials to Cuba will also be limited to those involved with the ongoing investigation or who have a need to travel related to the US national security or crucial embassy operations.

“The United States will not send official delegations to Cuba or conduct bilateral meetings in Cuba for the time being. Meetings may continue in the United States,” an official said.

Cuba has denied responsibility for the attacks and the State Department acknowledged the government’s efforts to investigate and its cooperation in facilitating the US investigation.

“But,” noted the State Department, “the government of Cuba is responsible for taking all appropriate steps to prevent attacks on our diplomatic personnel in Cuba.”

At a teleconference last Friday, a US State Department official said the US had not ruled out the possibility of a third country being responsible for the attacks and that was part of the investigation.