A group of American diplomats working in Havana were left with severe hearing loss due to a covert sonic device, US officials have claimed.
The group of diplomats first began experiencing the unexplained hearing loss last Autumn.
The incident caused a diplomatic row between the two countries, leading to two Cuban diplomats being expelled from Washington in May.
The American diplomats suffered a “variety of physical symptoms” – some so serious that they necessitated a return to the US, according to State Department spokeswoman Heather Nauert.
She added that the US does not “have any definitive answers” about the “source or the cause” of the incidents.
Officials, speaking under condition of anonymity, said an investigation revealed that the diplomats had been affected by a device emitting noises outside the range of audible sound.
The devices would have likely been installed close to or inside the residences of diplomats, which are maintained by the Cuban government.
Diplomatic relations between the US and Cuba were reinstated in 2015
Officials said it was unclear whether the incident was a deliberate attack, and added that other states such as Russia were being investigated for acts that the Cuban government may have been unaware of.
Cuba’s ministry of foreign affairs issued a statement saying it “has never permitted, nor will permit, that Cuban territory be used for any action against accredited diplomatic officials or their families”.
It stressed that it had treated the issue “with utmost seriousness” and insisted that Cuba complies rigorously with the 1961 Vienna Convention, which applies special protections to diplomats.
It said the decision to expel two Cuban diplomats from Washington had been “unjustified and unsubstantiated”.
The fiasco has rocked an already delicate diplomatic relationship between Cuba and the US, with diplomatic relations between the two countries only being restored in 2015 after a half century of hostilities.
The rapprochement, which had been mediated by Barack Obama and his Cuban counterpart Raul Castro, has already been troubled by Donald Trump’s moves to tighten travel restrictions and trade embargoes against Cuba.