Near the end of then-President Obama's term in 2016, the newly reopened US embassy situated on Havana's seaside Malecón boulevard was a sought-after posting, with diplomats jockeying to serve in a country where American foreign service officers were making history as the US and Cuba repaired long frayed diplomatic ties.

But late that year, US diplomats in their homes and hotel rooms in Havana began experiencing unexplained symptoms, such as dizziness and pounding headaches. These sometimes were accompanied by an unidentified "piercing directional noise" that sounded as if metal was being scraped across a floor.

Eventually 24 diplomats were diagnosed with brain damage that ranged from mild impairment to injuries "so severe they may never be able to return to their previous jobs," according to a newly declassified but heavily redacted 2018 State Department Accountability Review Board report.

What caused their injuries remains a mystery.

The State Department report, which was obtained by the National Security Archive research institute though a Freedom of Information Act request, concludes that the US government's response and investigation into the so-called Havana Syndrome may have been botched from the beginning.

"You see chaos, lack of organization, you see excessive secrecy, as the authors of the report put it, all of which compromised an initial investigation assessment of what was going on," said Peter Kornbluh, a senior analyst with the National Security Archive.

Part of the secrecy surrounding the incidents likely had to do with the fact that CIA officers working under diplomatic cover were among the first US officials impacted by the incidents and the first to depart Havana.

According to a timeline in the State Department report, the CIA informed the State Department in September 2017 of "its decision to withdraw its personnel from Havana for the foreseeable future."

The line is a rare public admission of a CIA station operating at a US Embassy, Kornbluh said.

"The CIA doesn't want to admit what everybody basically already knows, that they do have a contingent of operatives in most significant countries where they are trying to obtain intelligence," he said. "Cuba and the United States have been in a spy versus spy confrontation since the time of the revolution."

Two weeks after the CIA pulled its officers from Cuba, then-Secretary of State Rex Tillerson ordered a larger draw down of the embassy, according to the State Department report.

Tillerson's decision to reduce embassy staffing "does not appear to have followed standard Department of State procedures and was neither preceded nor followed by any formal analysis of the risks and benefits of continued physical presence of U.S. government employees in Havana," the report said.

"Of the many Department leaders interviewed by the Board, no one can explain why this has not happened," the report said, before offering one possibility for why the State Department did not follow its own safety protocols, which is redacted in the released report.

The cause of the diplomats' injuries also stumped US law enforcement, lawmakers, scientists and the intelligence community.

US investigators looked at the possibility that sonic weapons, neurotoxins, infectious diseases and mass hysteria could have been the cause. Canada said some of their diplomats suffered similar symptoms and also ordered a draw-down of their embassy in Havana.

US diplomats in China and Russia reported similar unexplained sudden health problems, raising the specter that American government officials working overseas were being widely targeted.

In December, a US-government funded study by the National Academy of Sciences said that "directed" microwave radiation was the most likely cause of symptoms observed in the affected diplomats working in Havana and China.

The study did not say what kind of device was capable of blanketing diplomats with microwave, or what countries possess that kind of previously unknown energy weapon.

Cuban investigators told CNN they did not agree with the study's conclusion. "There is no physical possibility of a microwave weapon, penetrating hotel rooms, houses, causing brain damage without burning the skin, without burning other tissues. It from the scientific point, untenable," said Dr. Mitchell
Valdes-Sosa, of the Cuba Neuroscience Center, who has been coordinating a Cuban government task force on the incidents.

Independent scientists consulted by CNN said that while there could be secret government programs they were not aware of, as far as they knew, there were no energy weapons that were capable of causing the damage described by US diplomats.

The official Cuban stance has always been that there were no attacks. "There was not a single evidence of an attack. There were symptoms," Johana Tablada, the Deputy Director for US Affairs at the Cuban Foreign Ministry, told CNN "It's very easy to establish what didn't happen and attacks did not happen. Most of the diplomatic community then and today remain confident and feel safe."

Cuban government officials complained that while they allowed the FBI to visit the island to investigate the issue, US officials have shared little of the
information they have gathered and, at times, insinuated that Cuba may be involved in a cover-up if an ally, like Russia, were behind the incidents.

Following the incidents and Trump's reversal of Obama's opening with Cuba, the US Embassy has become "a ghost ship manned by a skeleton crew" as one US diplomat, who served there after the draw-down and was not authorized to speak to the media, told CNN.

The diplomat said that, following the incidents, foreign service officers working in Havana lived several people to a house for security reasons and usually stayed for short tours of six months or less, making it difficult for them to get their bearings or develop contacts on the communist-run island.

The Biden administration has said they are reviewing all of the Trump administration's changes to Cuba policy, including the decision to pull diplomats from the embassy in Havana. Secretary of State Antony Blinken has been briefed on the diplomats injuries and would soon appoint a senior official to coordinate "continuing support to affected personnel," said State Department spokesman Ned Price at briefing last week.

Victor Alfonso Cedeño

Many Cubans who have been unable to visit family in the US since the incidents, are also hopeful that Biden will send US diplomats back to the island and restore services that had been suspended.

Following the drawdown of the embassy in 2017, consular services in Havana have been all but cut off for Cubans seeking visas to visit or emigrate to the United States. Thousands of Cubans have instead had to travel to third countries like Guyana to apply for visas.

Cuban illustrator Victor Alfonso Cedeño said he was turned down after he applied for an emergency medical visa from the embassy in 2020 so he could receive treatment in the US for a rare cancer he is suffering from.

"The answer we got was they couldn't receive the request because the consulate was closed," he said "Even though it's a medical situation, a situation of life or death.

Through their attorney, some of the US diplomats impacted by the alleged incidents in Havana said they regretted that Cubans had paid a price for their unexplained illnesses.

Mark Zaid, who represents eight diplomats and spouses that became sick in Havana, said that while he believes they were the victim of some kind of action by a US foreign adversary, Cuba was likely not directly responsible.

"It's unfortunate. I kind of look at the Cubans as second tier victims in this case. I know my clients, the State Department people who were there, they only have absolute praise," Zaid told CNN. "They thought things were going so great down there and would only want relationships to normalize and improve again."