WASHINGTON, March 21 (Reuters) - U.S. President Donald

Trump on Friday awarded Boeing ( BA ) a contract to build the

U.S. Air Force's most sophisticated fighter jet, known as Next

Generation Air Dominance, two sources familiar with the

situation said.

The NGAD program will replace Lockheed Martin's ( LMT ) F-22 Raptor

with a crewed aircraft built to enter combat alongside drones.

The plane's design remains a closely held secret, but would

likely include stealthiness, advanced sensors, and cutting-edge

engines.

The engineering and manufacturing development contract is

worth more than $20 billion. The winner will eventually receive

hundreds of billions of dollars in orders over the contract's

multi-decade lifetime.

For Boeing ( BA ), the win marks a reversal of fortune for a

company that has struggled on both the commercial and defense

sides of its business. It is a major boost for its St. Louis,

Missouri, fighter jet production business.