SEATTLE ( TheStreet) -- Delta ( DAL) is wasting no time bulking up in Seattle. The carrier said Tuesday it will add two new Seattle destinations: Portland and San Diego. That would bring the total number of destinations to 18. Four daily San Diego non-stops will begin June 2, four daily Portland, Ore., non-stops will begin Sept. 2, and the number of summer seasonal flights to Anchorage, Alaska, will increase from one to two on June 5. The competition involved in Delta's Seattle buildup, where code-share partner Alaska ( ALK) already operates a hub with about 300 daily departures, is a hot topicin the airline industry. By next summer, Delta will have nine daily international departures from Seattle, including six to Asia, and it wants to support that with domestic feed. Delta said last month it will add seven daily Seattle-San Francisco flights by June 2014; four daily Seattle-Las Vegas flights by April, bringing the total to five; and two daily Seattle-Los Angeles flights in June, bringing the total to seven. Alaska's reaction to the buildup was the subject of repeated questions on its third-quarter earnings call last month. "As we move forward, there are going to be places where it's going to be in our interest to work with Delta and we're going to support them, (where) they're growing internationally," said Alaska CEO Brad Tilden. "And then there are places where they are growing in North-South markets that have been long-term core markets for Alaska Air Group (and) in those markets, we will compete and we'll defend what we've built over the next years." On Tuesday, Delta said it would double mileage awards and qualification for its Medallion program, which enables upgrades, on all six of its Seattle-West Coast routes through Oct. 31, 2014. "We have continued to strategically add service from key markets in an effort to support passenger demand for our expanding international destinations," said Mike Medeiros, Delta's vice president -- Seattle. "Delta's most recent additions will provide our customers with one-stop access to and from several of the top international and domestic destinations via our growing global gateway in Seattle." Delta currently operates 36 peak-day departures to 15 destinations from Seattle.