The first variant of the F-35 joint strike fighter has been cleared fit to deploy, the Pentagon announced on Friday, a mega milestone in the multinational effort to field the most expensive weapons program in history.

The Marine Corps version of the jet, known as the F-35B, uses rotating lift fans to take off and land vertically from austere landing strips and large-deck helicopter carriers at sea. A squadron of 10 jets from Marine Fighter Attack Squadron 121, based at Marine Corps Air Station Yuma, Ariz., was declared ready for worldwide deployment.

The U.K., which is one of the program's foreign partners, also plans to purchase F-35Bs and fly them from its carriers.

Marine Commandant Gen. Joe Dunford announced on Friday his full confidence in the controversial and expensive aircraft.

"Prior to declaring [initial operating capability], we have conducted flight operations for seven weeks at sea aboard an L-Class carrier, participated in multiple large force exercises, and executed a recent operational evaluation which included multiple live ordnance sorties," Dunford said in a statement." The F-35B's ability to conduct operations from expeditionary airstrips or sea-based carriers provides our nation with its first 5th generation strike fighter, which will transform the way we fight and win."

The fighter jet will eventually replace the AV-8B Harrier jump jet and F/A-18 Hornet strike fighter for the Marine Corps.

Next up for the program will be the Air Force F-35A, which takes off and lands from conventional runways. It's expected to be declared ready next year, following by the aircraft carrier version for the Navy in 2018.

The program's eight partner nations are Australia, Canada, Denmark, Italy, the Netherlands, Norway, Turkey and the U.K.

Israel, Japan and South Korea plan to purchase the aircraft.