US pulls more than half of Cuba embassy staff after 'sonic attacks' and warns against travel

The United States is warning Americans against visiting Cuba and ordering more than half its government personnel to leave the island, senior officials said.

It was a dramatic response to what the US described as "specific attacks" on diplomats, including in hotels.

The decision deals a blow to already delicate ties between the US and Cuba, longtime enemies who only recently began putting their hostility behind them.

The embassy in Havana will lose roughly 60 per cent of its US staff, and will stop processing visas in Cuba indefinitely, the American officials said.

In a new travel warning to be issued Friday, the US will say some of the attacks have occurred in Cuban hotels, and that while American tourists aren't known to have been hurt, they could be exposed if they travel to Cuba.

Tourism is a critical component of Cuba's economy that has grown in recent years as the US relaxed restrictions.

Almost a year after diplomats began describing unexplained health problems, US investigators still don't know what or who is behind the attacks, which have harmed at least 21 diplomats and their families, some with injuries as serious as traumatic brain injury and permanent hearing loss.