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The United States Department of Defense has awarded a $2.9 billion contract to Pratt & Whitney, a subsidiary of RTX, to produce and deliver 141 F135 engines for the F-35 Lightning II fighter jet. The engines will be installed in the aircraft’s 18th production lot.

Deliveries are scheduled to be completed by February 2028, with an initial $2 billion already allocated at the time of signing. Both U.S. armed forces and international customers who operate the F-35 are set to receive engines under the agreement, ensuring production lines remain on schedule and operational fleets continue to expand.

According to the U.S. Department of Defense statement, This modification adds scope for the production and delivery of 141 F135 propulsion systems in support of Lot 18 F-35 aircraft production for the Joint Strike Fighter program for the Air Force, Marine Corps, Navy, F-35 Cooperative Program Partners, and Foreign Military Sales customers.

Fleet growth and operational record

The contract marks another step in sustaining the F-35 program, which has become one of the most significant multinational defense efforts in modern history. The Pratt & Whitney has already delivered more than 1,200 F135 engines, which together with the growing fleet of F-35 aircraft, are now in service with 12 countries worldwide.

The F135 engine has logged more than one million flight hours across multiple theaters, increasingly in combat and operational missions. The engine provides the high thrust and reliability required to operate in demanding environments, from carrier operations at sea to austere bases in forward-deployed regions.

The engine’ performance has been central to the F-35’s reputation as a versatile, fifth-generation fighter capable of fulfilling air superiority, strike, and intelligence-gathering roles.

International participation

The F-35 program brings together a wide network of partners and customers. Core participants include the United States, the United Kingdom, Italy, the Netherlands, Canada, Australia, Denmark, and Norway, all of whom are directly involved in the development and production of the jet. In addition, countries such as Japan, South Korea, Israel, Finland, and Belgium have joined as foreign military sales customers, expanding the program’s reach.

For many of these nations, the F-35 represents not only a technological leap but also a way to enhance interoperability with U.S. and NATO forces. Delivering new engines to both American and international fleets underlines the program’s role in strengthening collective defense structures and sustaining long-term multinational cooperation.

Future modernization plans

Pratt & Whitney plans to introduce upgraded versions of the F135 engine beginning in 2028. These enhancements are expected to generate savings of around $40 billion over the lifetime of the global fleet, while providing improved efficiency and reliability.

The modernization effort is aimed at meeting the growing demands of the F-35 Lightning II as the aircraft evolves into its Block 4 and later variants. These future models will carry more advanced sensors, electronic warfare equipment, and an expanded range of weapons.

To operate effectively with this increased payload and onboard technology, the aircraft requires an upgraded propulsion system capable of delivering additional power and resilience.

Enhanced Power and Cooling System

RTX companies are also developing the Enhanced Power and Cooling System, or EPACS. The program has reached the prototype testing stage and is designed to increase the electrical power available to the aircraft while improving its cooling capacity.

This capability is particularly important as future modifications to the F-35 will include high-demand electronic systems and next-generation computing power. The EPACS module will allow the jet to integrate these systems without risking overheating or energy shortfalls, ensuring that it remains combat-ready against advanced threats.

Strategic importance

The Pentagon’s decision to commit to another large production batch of engines reflects the strategic role the F-35 plays in U.S. and allied defense. The fighter is deployed across Europe, the Middle East, and the Indo-Pacific, where it has become an important tool of deterrence and power projection. Its ability to operate with partner nations is central to NATO’s collective defense posture and to U.S. security guarantees in Asia.

Ensuring a steady supply of engines also has an industrial dimension. The F-35 program supports tens of thousands of jobs across the United States and in partner countries. Pratt & Whitney’s continued role in producing and modernizing the propulsion system highlights the depth of the defense industrial base and the importance of sustaining long-term contracts that provide stability for both the manufacturer and military operators.

Balancing costs and capabilities

While the F-35 program has faced criticism in the past for high procurement and sustainment costs, efforts like the engine modernization program are designed to address those concerns. By introducing more efficient engines and upgrading systems such as EPACS, the Pentagon and its partners aim to lower the long-term cost of ownership while enhancing combat effectiveness.

The projected $40 billion in lifetime savings from the upgraded F135 is significant for both the U.S. and international operators, who will benefit from reduced maintenance requirements and improved performance. These savings are also intended to help offset the cost of integrating new technologies into the fleet over the coming decades.

Broader defense investments

The contract with Pratt & Whitney comes at a time when the United States is placing renewed emphasis on modernization across multiple domains. In addition to advanced fighter aircraft, the Department of Defense is investing heavily in hypersonic weapons, missile defense, and space-based capabilities. The F-35 program remains central within this broader strategy, providing a proven platform that can be continuously upgraded to meet emerging threats.

For the Pentagon, securing the propulsion supply chain for the F-35 ensures that the aircraft can continue to serve as the backbone of allied airpower. For international partners, the steady delivery of engines signals Washington’s commitment to sustaining the program and maintaining interoperability across global fleets.

With deliveries scheduled through 2028 and upgrades planned from that year onward, the F135 engine will remain a critical enabler of the F-35’s capabilities, shaping the aircraft’s role in U.S. and allied military operations for decades to come.