Donald Trump 'to ask Cuba to cut Washington Embassy staff by 60%'

The US request marks yet another major setback for relations between the United States and Cuba, two countries that only recently renewed diplomatic relations after a half-century of hostility. It comes as the US seeks to protect its own diplomats from unexplained attacks that have harmed at least 21 Americans in Havana with ailments that affected their hearing, cognition, balance and vision.

The State Department is expected to announce the decision on Tuesday, officials said, though they cautioned no decision was formalised until publicly announced. The officials weren't authorised to discuss the plan publicly and requested anonymity.

Secretary of State Rex Tillerson discussed the plan Monday with President Donald Trump, one of the officials said.

Cuba has denied involvement in the attacks. Though Havana is likely to view the move as unwarranted retaliation, US officials said the goal wasn't to punish the communist-run island, but to ensure both countries have a similar number of diplomats in each other's capitals. The United States will formally ask Cuba to pull the diplomats, but won't expel them forcefully unless Havana refuses, the officials said.

Tensions between the two neighbours have been escalating amid serious US concern about the unexplained attacks on Americans in Havana.

On Monday, The Associated Press reported that US spies were among the first and most severely affected victims.

Though bona fide diplomats have also been affected, it wasn't until US spies, working out of the embassy under diplomatic cover, reported hearing bizarre sounds and experiencing even stranger physical effects that the United States realised something was wrong, several individuals familiar with the situation said. The mysterious "health attacks" started within days of President Donald Trump's election in November.