WASHINGTON -- It is a mysterious episode seemingly ripped from the pages of a Cold War spy novel.
In recent months, several U.S. and Canadian diplomats posted in Havana have reported experiencing unusual medical symptoms, including impaired hearing, sometimes so severe that they had to return home.
News of the ailments surfaced this week when the State Department announced that it had expelled two Cuban diplomats from Washington because of an "incident" in Havana that harmed U.S. personnel there.
That came despite vastly improved relations between Washington and Havana since restoration of diplomatic relations under former President Barack Obama.
On Thursday, the Canadian government added its voice.
Canadian officials "are aware of unusual symptoms affecting Canadian and U.S. diplomatic personnel and their families in Havana," the Canadian global affairs ministry said in a statement.
It said Canada was working with U.S. and Cuban authorities to "ascertain the cause."
U.S. State Department spokeswoman Heather Nauert would not provide details except to say the episode had caused medical but non-life-threatening problems for an unspecified number of U.S. Embassy personnel based in Havana.
The Associated Press, one of the few Western news outlets with offices in the Cuban capital, reported from Havana that the injuries may have been caused by covert sonic equipment that Cuban intelligence officers had secretly installed in the embassies or residences of staff.
The AP said at least one of the American diplomatic personnel suffered permanent hearing loss.