UK leader 'bitterly disappointed' by US ruling on Bombardier

U.K. Prime Minister Theresa May says she is "bitterly disappointed" by the U.S. government's decision to slap duties of almost 220 percent on Bombardier's C series aircraft.

May took to Twitter on Wednesday to say Britain will work with the Montreal-based company to protect jobs, including some 4,000 in Northern Ireland. May has a key alliance with the Northern Ireland-based Democratic Unionist Party to support her minority government in Parliament.

The U.S. Commerce Department on Tuesday ruled in favor of U.S. aircraft maker Boeing, which alleged that Bombardier used unfair government subsidies to sell aircraft at artificially low prices.

U.S.-based Delta Air Lines, which plans to buy as many as 125 of Bombardier's new CS100 aircraft, has argued that Boeing doesn't even make the 100-seat planes it needs.