However, it's not expected to resolve the mystery of what some have alleged were "sonic attacks" amid a public disagreement between two Republican members of the committee holding the hearing over whether the diplomats were victims of "attacks".
"There are some people with symptoms happening that are unexplained", Flake, R-Ariz., told CNN last week while visiting the island. "I think that lends credence to my argument, which is this is an attack that is so sophisticated against 24 Americans that it had to be conducted on behalf of a nation-state, whether it was rogue elements of the Cuban regime, the regime itself or a third-party country".
Initially officials suggested the Americans had been targeted by some sort of acoustic weapon, although news reports now say the Federal Bureau of Investigation has been unable to confirm this theory. "We shouldn't be using that word".
Dr. Charles Rosenfarb, the State Department's chief doctor, also dismissed speculation that the illnesses were psychosomatic.
"While we can't deduce how they did it, we know it happened", he explained.
A man works outside of the U.S. Embassy in Havana, Cuba, September 29, 2017. At that point, more than 20 officials had gotten sick.
"I categorically reiterate that the Cuban government has no responsibility whatsoever in the health conditions reported by US diplomats", she said.
USA investigators believe American diplomats and others in Havana may have been attacked by a sonic weapon earlier this year causing them to suffer hearing loss, dizziness, headaches and fatigue.
Canadian diplomats and family members reported similar ailments.
"It's a documented fact that 24 USA govt officials & spouses were victims of some sort of sophisticated attack while stationed in Havana", he said in a series of tweets.
The State Department waited almost one year before standing up an independent investigative panel, known as an Accountability Review Board, to probe the unexplained attacks on USA personnel working in Cuba and their family members.
A senior USA official told senators at a Senate hearing Tuesday that Secretary of State Rex Tillerson will open a high-level investigation into unexplained "sonic attacks" that physically affected diplomats at the embassy in Cuba a year ago.
The Accountability Review Board is an internal State Department mechanism to review security incidents involving diplomatic personnel. The most recent medically-confirmed attack occurred August 21, 2017.
"Why wasn't it set up according to law?" he asked Palmieri and Todd Brown, the State Department's diplomatic security assistant director for worldwide programs.
"As Secretary Tillerson has stated, we will not share information that violates individuals' privacy or reveals their medical conditions", the State Department told CNN.
But US scientists have no idea what kind of weapon or agent could cause the symptoms, or whether the sounds heard were a by-product of the attack or its means of delivery. While the injuries came to light in May, Tillerson just last month authorized the review. Marco Rubio of Florida, a critic of closer ties to Cuba.
"People were hurt and the Cubans know who was responsible", Rubio said. "It's as simple as that".
At the end of September Trump ordered the removal of more than half of the U.S. embassy staff in Havana and shortly after he expelled 15 Cuban diplomats from Washington.
Cuban diplomat Josefina Vidal Ferreiro rejected the charges in a statement released late on Tuesday. "There is a transition going on in terms of leadership", Flake told CNN.