The US State Department is pulling out all families of employees and nonessential personnel from Cuba, after a string of mysterious sonic attacks against US diplomats, according to two US officials. Photo: CNN

The American Embassy will continue to operate with a reduced staff. The sources said the US will stop issuing visas in Cuba effective immediately.

The decision came after an exhaustive review of US diplomats' safety in Havana and discussions with the Cuban government, which has vociferously denied any involvement in the attacks.

In a meeting with US Secretary of State Rex Tillerson Tuesday, Cuban Foreign Minister Bruno Rodríguez denied that Cuba was involved in attacks on diplomats and said the United States was politicizing the incidents. He said his government would continue to work with US authorities investigating the attacks.

"The secretary told him independent of who is doing it, the Cubans have a responsibility for the safety and well being of our people," a senior State Department official told CNN.

At least 21 US diplomats and family members have been affected by the incidents that began in November, causing a baffling array of maladies from hearing loss to dizziness to concussions.

US officials say there may have been as many as 50 attacks, a senior US official told CNN, the most recent in August. Some victims have had long lasting symptoms and, in at least one case, permanent hearing loss. 

Despite the harassment, some US diplomats told CNN they did not want to depart, saying the reductions likely played into the hands of whoever was behind the attacks and would leave the embassy understaffed during a crucial period where Raul Castro is expected to step down as president of Cuba.

Investigators haven't determined the cause of the incidents, but US officials told CNN they are convinced someone has targeted American diplomats in Havana with a sophisticated device never deployed before, at least not against US personnel.

Canadian diplomats have suffered similar health problems, according to US and Canadian officials.

But seven months after complaints to Cuban officials and assurances from Castro that the incidents would be investigated, US officials are frustrated by the lack of progress and have considered a range of options from scaling back the embassy to limiting the number of people who risk exposure to a full-on shuttering of the embassy, three senior US officials told CNN.

"We have to consider it. We thought we had corralled this, and then the two cases in August took place," a senior US official said. "It is not as if the attacks address individual personnel officers. Our personnel is broadly at risk. So we have to consider next steps because we need to protect our people."

A setback to US-Cuban relations

The removal of the diplomats is a setback to US-Cuban relations following the "new beginning" heralded by former President Barack Obama when he and Castro agreed to restore full diplomatic relations and to try to move past decades of Cold War tensions and mistrust. It comes at a crucial moment as Castro prepares to step down as President in February and Washington needs eyes and ears on the ground.

The Obama administration relaxed restrictions on US citizens visiting the island and, for the first time in over 50 years, re-established direct flights as well as allowing US cruise ships to travel to the island.

The State Department removed Cuba from its list of countries that support state terrorism and Obama visited the island in 2016, the first sitting US president to do since the Cuban revolution.