Delta Air Lines on Tuesday announced three new routes from Sea-Tac Airport.

Delta will offer daily, round-trip flights to Kansas City and Washington-Dulles, which begin June 8, and to Indianapolis starting June 18.

The airline said it will also add more flights to existing routes -- Las Vegas, JFK in New York, Orlando, and Medford, Oregon during spring and summer. Delta's summer service between Seattle and Cincinnati will also to expand year-round, and Delta will offer seasonal service to New Orleans in February and March.

The news comes the same day Alaska Airlines announced the 13 routes it will begin offering out of Paine Field in Everett.

Atlanta-based Delta and Seattle-based Alaska have been in a turf war at Sea-Tac Airport for several years, but Alaska still dominates the market there.

Sea-Tac says Alaska had 49.7 percent of the total number of passengers that came through the airport in 2016 while Delta had 20.6 percent. Delta led Alaska in international traffic at Sea-Tac, 34.6 percent to 20.4 percent.