Korean Air signed a memorandum of understanding (MOU) with Boeing in the U.K. on Monday (local time), marking a significant commitment to expand its fleet with the purchase of 20 Boeing 777-9 aircraft and 20 Boeing 787-10 Dreamliners, with an option to purchase 10 more of the largest variant of the 787 Dreamliner in the future, the airline said on Monday.

The size of the MOU is estimated to be worth around 30 trillion won ($22 billion).

The carrier explained that its latest agreement with the U.S. aircraft maker is intended to upgrade and expand its wide-body fleet.

With their capability of long-haul flights to regions such as North America and Europe, the 777-9 and 787-10 are also expected to play an important role after Korean Air’s acquisition of Asiana Airlines.

“The addition of the Boeing 777-9 and 787-10 aircraft marks a significant milestone in our strategic objective to expand and 커뮤니티 upgrade our fleet,” said Korean Air Chairman Cho Won-tae, who is also known by his English name, Walter Cho.

“This investment underscores our commitment to providing a best-in-class flying experience. These new airplanes will elevate passenger comfort and enhance operational efficiency, while significantly reducing carbon emissions, supporting our long-term commitment to sustainable aviation.”