Alaska Airlines has flown internationally to Canada and Mexico for some time. But they are adding a third international destination. Starting May 21 you can book a flight to Costa Rica on Alaska Airlines. The flights will begin to San Jose on October 31 and Liberia the following day.
The announced flights (below) are only out of LAX (at least for now). While Seattle is Alaska’s hub, I can see why it would make more sense to fly out of a southern city.