American Airlines will begin flying to India and the United Kingdom from Seattle, part of a renewed and boosted alliance with Alaska Airlines.

Fort Worth-based American Airlines’ codeshare deal with Seattle-based Alaska Airlines was set to expire in April, but the new agreement means customers of both will be able to earn miles on either airline, book flights through both systems and use one another’s lounges.

Alaska also plans to join American’s Oneworld alliance by the summer of 2021.

With the expanded deal, American will start flying from Seattle to Bangalore, India, in October and from Seattle to London Heathrow Airport in March 2021.

The two airlines have been collaborating since 1999, but the relationship fizzled when Alaska bought the assets of Virgin America in 2016. That gave Alaska too many overlapping destinations with American in the United States. In October, the two sides decided to scale back their mileage partnership.

Now, they’re back together.

American’s vice president of network planning Vasu Raja said the new flights gave the company the opportunity to expand out of Seattle, a market where it didn’t previously have enough connections to justify flights to places like India and the United Kingdom.

“It’s going to create more options for us,” Raja said. “These partnerships should result in the growth of American Airlines.”

The Seattle to Bangalore flight will be the second-longest in American’s network at about 15 hours on a Boeing 787 Dreamliner. The longest is from DFW to Hong Kong and takes about 19 hours. Since it flies a northern route near Alaska, Seattle is American’s closest airport for flights to India.

American Airlines flew to New Delhi until 2015. But Raja said the company has been eager to get back, and an India flight is among its most frequently requested from customers.

American has spent two years bulking up its international network and expanding back into parts of the world it had once abandoned. It has recently added flights from DFW Airport to Tel Aviv, Israel, and from Philadelphia to Casablanca, Morocco. America also announced a deal this month with Brazilian low-cost carrier Gol to bulk up its destinations in South America.

Raja called the Alaska-American deal a “West Coast international alliance." They will once again codeshare on domestic flights and expand to international routes from Los Angeles International Airport and SeaTac International Airport near Seattle.

The deal needs regulatory approval.