MIAMI — Delta Air Lines has announced today the end of its partnership with Alaska Airlines, to be effective on May 1, 2017. After this date, both carrier will no longer codeshare their flights, and sales of Delta and Alaska-coded flight numbers will cease as well.

“The decision is a positive milestone for both airlines as Alaska focuses on its merger integration with Virgin America, and Delta focuses on creating more customer choice at its Seattle-Tacoma International Airport hub, where it now operates more than 150 peak-day flights to more than 40 destinations,” the Atlanta-based carrier said in a statement.

While the partnership between both carriers ends, the airlines will retain an interline agreement, which will allow them to offer customers both ticketing and baggage connectivity.

Delta’s master plan to become “the region’s global carrier” — and turn Sea-Tac Airport into Delta’s West Coast gateway to Asia — started by expanding in Seattle with flights to Anchorage and other western markets traditionally served by Alaska, and progressively overlapping Alaska’s destinations.

“We view Seattle and the Pacific Northwest as one of the most important markets in the country, with strong economic growth, cultural diversity and some of the world’s most innovative brands and minds,” said Mike Medeiros, Delta’s Vice President – Seattle. “Our focus now is earning the long-term trust of Pacific Northwest customers by demonstrating the value of partnering with a global airline.”

By 2017, Delta plans to offer 150+ daily flights from Seattle, a giant leap from the 38 flights it was offering from Seattle to 15 destinations at the beginning of 2014.