American Airlines is to close its International Reservations Office in Dublin, a move which will affect 130 workers.
The airline says its "regrettable" decision was taken because "significant losses" means it needs to evaluate all areas of the business for efficiency and cost savings.
The company is now entering into a consultation process with trade unions.
American Airline's daily flight operations between Dublin and Chicago O'Hare are unaffected by today's announcement and will continue to operate as scheduled.