NEW YORK: The United States may again close its embassy in Cuba, which reopened two years ago after a half-century standoff, following a series of mystery “health attacks” on its diplomats, Secretary of State Rex Tillerson said Sunday. At least 21 members of the US mission in Havana and a smaller number of Canadians have suffered brain injuries and hearing loss in what have been reported as “acoustic attacks,” although US officials say their origin remains unclear. The incidents began last year, and the latest was recorded in August, despite US authorities having complained to Cuban officials in February and having expelled two Cuban diplomats from Washington in May. Some of those hurt were evacuated to Florida and some treated in place. With the injury toll continuing to rise, and no explanation for what Washington has called an “unprecedented incident,” some US lawmakers have called for the embassy to be closed down once again.