Low-cost carrier Norwegian Air is to stop direct flights between Northern Ireland and the US from next month.
The company said it was down to "customer demand".
It began flights from Belfast International to airports near New York and Boston last year. The last departures will be on 27 October.
Belfast International said the airline was "moronically channelling much greater levels of Northern Ireland passengers on to Dublin flights".
A spokesperson said the airport was "extremely disappointed" by the decision.
Norwegian Air said the move followed a "comprehensive review" and Northern Ireland's passengers would be "well-served" by the airline's flights to the US from Dublin, Shannon and Cork.
The Norwegian Air flights were to Stewart International Airport, about 70 miles from New York, and TF Green Airport, 60 miles from Boston.
Last February, the airport said the airline's arrival was "the best possible boost for Northern Ireland", after United ended its daily Belfast-Newark service.