Lockheed Martin has received a $450 million contract modification for additional Lot 10 F-35 Lightning II Air System integration work.

The contract modification supports fifth generation fighter production for planes to be sold to South Korea under the U.S. Foreign Military Sales program. Lockheed Martin will also be tasked with providing non-recurring engineering work.

The U.S. Department of Defense says the work will be performed at the company's facility in Fort Worth, Texas, and expects it to be complete by August 2019.

Lockheed Martin received all funding for its foreign military sale project at the time of the contract modification award. The Naval Air Systems Command in Patuxent River, Ma., is listed as the contracting activity.

South Korea signed off on F-35 fighter jets in September 2014. The country plans to procure 40 of the next-generation aircraft, and expects deliveries to begin in 2018 and conclude in 2021.