WASHINGTON — The price of a conventional F-35A model has fallen below $90 million for the first time through a deal announced Sept. 28 between the Pentagon and Lockheed Martin.

The Defense Department’s F-35 Joint Program Office and F-35 prime contractor Lockheed have finalized an $11.5 billion contract for the 11th batch of F-35s. The deal comprises 141 new jets and follows a handshake deal between the two parties that was announced in July.

The agreement pushes the cost of the F-35A conventional model — used by the U.S. Air Force and most foreign buyers — to $89.2 million per aircraft, a 5.4 percent reduction from the $94.3 million in the 10th batch of aircraft.

The more expensive "B" and "C" models incurred even bigger price cuts. The Marine Corps’ F-35B short-takeoff-and-vertical-landing variant’s cost decreased 5.7 percent from $122.4 million to $115.5 million, while the F-35C carrier variant dropped a whopping 11.1 percent from $121.2 million to $107.7 million per unit.

The finalized agreement comes on the heels of another first for the platform. On Thursday, Marine Corps F-35Bs were flown in combat for the first time by the U.S. military, conducting successful airstrikes on an unnamed fixed target.

Although the Marine Corps and Air Force have already begun using their Joint Strike Fighters operationally, F-35 program leaders from government and industry remain focused on bringing down production costs to $80 million per unit by 2020 — a step seen as critical for the services to begin buying greater numbers of aircraft.

“Driving down cost is critical to the success of this program,” said Vice Adm. Mat Winter, the F-35 program executive officer. “We are delivering on our commitment to get the best price for taxpayers and war fighters.”

“This agreement marks a significant step forward for the F-35 program as we continue to increase production, reduce costs and deliver transformational capabilities to our men and women in uniform,” said Greg Ulmer, Lockheed’s F-35 vice president and general manager. “As production ramps up and we implement additional cost savings initiatives, we are on track to reduce the cost of the F-35A to $80 million by 2020, which is equal to or less than legacy aircraft, while providing a major leap in capability.”

Deliveries of low-rate initial production lot 11 are set to begin in 2019. LRIP 11 is the largest production batch so far, covering 91 jets for the U.S. military, 28 for F-35 international partners that paid into the development of the aircraft and 22 jets for Foreign Military Sales customers.

The government contracts separately for the F-35’s engines, the F135 built by Pratt & Whitney, but the pricing information issued Friday includes both the airframe and the engine. The parties reached a $2 billion agreement for the LRIP 11 engines in May.

With the lot 10 contract under their belts, the Pentagon and Lockheed are set to begin negotiations on lots 12, 13 and 14, which will be grouped together as a block buy that will initially serve international customers but could also accommodate the U.S. services as early as lot 13.