The American flag flies at the U.S. Embassy following a ceremony August 14, 2015, in Havana.
Washington CNN  — 

The State Department announced Friday it will continue to staff its embassy in Havana at the minimum level required to perform “core diplomatic and consular functions” due to concerns about “health attacks” on staff.

The move comes amid continued uncertainty about the cause of the attacks, which affected at least 24 diplomats and family members in 2016 and 2017.

At a congressional hearing in January, US officials detailed how personnel came to experience a variety of symptoms including sharp ear pain, headaches, ringing in one ear, vertigo, disorientation, attention issues and signs consistent with mild traumatic brain injury or concussion. In nearly all cases, the ailments were preceded by some sort of “acoustic element,” such as a “high-pitched beam of sound” or a “baffling sensation akin to driving with the windows partially open in a car.”

The embassy had been operating under ordered departure status since September, but the status was set to expire on Sunday. The new staffing plan will effectively extend the staff reductions indefinitely.

“The embassy will operate as an unaccompanied post, defined as a post at which no family members are permitted to reside,” the statement continued.

“We still do not have definitive answers on the source or cause of the attacks, and an investigation into the attacks is ongoing,” the department notes. “The health, safety, and well-being of U.S. government personnel and family members are of the greatest concern for Secretary Tillerson and were a key factor in the decision to reduce the number of personnel assigned to Havana.”

Cuban officials previously denied they had anything to do with the diplomats’ health problems and said the whole affair might be the result of mass hysteria.

The head of US affairs for the Cuban Foreign Ministry, Carlos Fernández de Cossío, tweeted Friday night that the State Department’s decision “responds to political motivations and has no relation to the security of their officials in Havana.”

On a trip to Havana in February, Sen. Patrick Leahy, D-Vermont, said the two countries needed to find a way to resolve the crisis before relations were permanently damaged.

“I feel it’s absolutely essentially that we get our embassy up to full staffing,” Leahy said at a news conference in Havana after meeting with Cuban president Raul Castro. “It’s essential that Cuba get their embassy back fully staffed. There’s no way we are going to have the improvement of the relationship that is going to be good for Cuba and the United States if we don’t have the personnel that is here to do it.”

A State Department official tells CNN that Cuban citizens will still need to travel to third countries in order to apply for US visas, except in exceptional circumstances or in cases of official diplomatic travel.

“We understand this is a significant change and an inconvenience for visa applicants,” the official said. “The number of consular personnel in Cuba at this time, however, does not allow us to continue normal visa operations in Havana.”

The termination of consular services in Havana means obtaining family reunification and cultural exchanges will be much more expensive and time consuming for Cubans.

“Maybe we will have to wait four or eight more years,” said Lizt Alfonso, a renowned Cuban choreographer whose dance company had to cancel performances in the US in 2017 after the US Embassy stopped offering visa appointments. “Maybe we won’t live to see it. Our children and our grandchildren will live to see it and all of this will be forgotten, and then they will say, ‘How stupid so much time was lost and all the good and beautiful things that they could have done.’”

While the US government has not accused the Cuban government of being behind the incidents, Tillerson has said he holds Cuba responsible for allowing them to continue.