FORT WORTH, Texas, Nov. 20, 2012 /PRNewswire/ -- Three Lockheed Martin (NYSE: LMT) F-35B short takeoff/vertical landing (STOVL) aircraft were officially delivered to the U.S. Marine Corps during ceremonies at Marine Corps Air Station Yuma, Ariz., today. The three jets are assigned to Marine Fighter Attack Squadron 121 residing with the host Marine Aircraft Group 13. (Photo: http://photos.prnewswire.com/prnh/20121120/DA17334) "For more than 50 years, it has been our mission to support the Marine Corps mission, and we're honored to deliver the first three F-35B STOVL aircraft to Marine Fighter Attack Squadron 121," said Bob Stevens, Lockheed Martin chairman and chief executive officer. "The F-35B is the world's only 5th generation, supersonic, stealthy combat aircraft that can also hover, take off and land virtually anywhere Marines are in action. Through the hard work and dedication of the military and contractor team, the F-35B will define the future of Marine Corps aviation." Official welcoming ceremonies at Yuma marked the handover of the jets to the Marines. The delivery of the first three operational-coded 5 th generation F-35B STOVL fighters marks the beginning of STOVL tactical operational training at Air Station Yuma. These three aircraft increase the number of STOVL aircraft delivered to the Marine Corps to 16 and bring the total number of F-35s delivered in 2012 to 20. Currently, 13 Marine Corps STOVLs are assigned to the 2nd Marine Aircraft Wing's Marine Fighter/Attack Training Squadron 501 at Eglin AFB, Fla., supporting pilot and maintainer training. The F-35 Lightning II is a 5 th generation fighter, combining advanced stealth with fighter speed and agility, fully fused sensor information, network-enabled operations and advanced sustainment. Three distinct variants of the F-35 will replace the A-10 and F-16 for the U.S. Air Force, the F/A-18 for the U.S. Navy, the F/A-18 and AV-8B Harrier for the U.S. Marine Corps, and a variety of fighters for at least nine other countries. Lockheed Martin is developing the F-35 with its principal industrial partners, Northrop Grumman and BAE Systems.