Ben Rhodes, a top national security official in the Obama White House, suggested in a new interview that the Russians could be behind the mysterious health incidents impacting U.S. officials in Cuba, which have been alleged to be "sonic attacks."

More than a year after the illnesses began, investigators still have not been able to draw any conclusions about the "attacks" or who may have been behind them.

Rhodes, who served as deputy national security adviser, said he doesn't think it was the Cuban government, according to the Guardian.

“I really do not believe it is the Cuban government,” Rhodes said. “Whether it’s a third party like Russia, or whether that is some harder-line faction in Cuba, to me it is someone with a motivation to kill the relationship or set it back. And unfortunately, they’ve succeeded.”

The Obama administration in its final years worked to restore long-strained relations between Cuba and the U.S.

Roughly two dozen U.S. personnel and family members fell ill in their hotels and homes starting in Havana starting in November 2016, according to the U.S. government. The U.S. officials reported hearing some sort of loud noise that was followed by symptoms, including hearing loss and dizziness. This prompted speculation that there could have been some sort of sonic weapon.

The U.S. withdrew most of their diplomats and officials out of Havana and did the same to Cuban diplomats in Washington.

Secretary of State Rex Tillerson has said in the past that he is convinced there were "deliberate attacks," and while the U.S. has stopped short of blaming the Cubans, Tillerson last month placed responsibility on the island nation for putting a stop to the incidents.

The Senate held a hearing on the "sonic attacks" last week, and State Department officials said they are still puzzled by the matter.

Cuba, which is conducting its own investigation, has refuted the idea of sonic attacks.

A similar acoustic attack last year was reported at the U.S. embassy in Uzbekistan, which was once a part of the Soviet Union, raising suspicions of Russia involvement in the incidents last year. However, the State Department denied there were any incidents in Uzbekistan.