India’s purchase of the S-400 air defense system from Russia has thrown a wrench into its negotiations to join the F-35 program.
Shortly after taking office for a second time, President Donald Trump sought to increase military sales to India. He floated the idea that future deals could include the fifth-generation Lockheed Martin F-35 Lightning II. However, there may be a sticking point: India has begun to operate the Russian-made S-400 “Triumf” air-defense system, which Washington and NATO leadership have warned is incompatible with the stealth fighter.
NATO member Turkey was infamously expelled from the F-35 program after it adopted the S-400, owing to concerns that operating both would jeopardize the security of the Lightning II. Ankara has yet to find its way back into the program, but there are few options for Turkey to move forward without ditching the Triumf.
Under a $5.4 billion deal concluded by New Delhi and Moscow in 2021, India was to receive five squadrons of the S-400. Three have been delivered and are now in operation, deployed to northwest and east India to counter threats from China and Pakistan. The Indian military has been awaiting the arrival of the fourth and fifth squadrons of Russian air defense systems, which are now scheduled to arrive in 2026 and 2027—although these deliveries had been delayed due to the ongoing war in Ukraine. On the sidelines of the recent Shanghai Cooperation Organization (SCO) meeting in Qingdao, China, Russian officials confirmed that Moscow would deliver an additional two S-400 systems to New Delhi in the near future.
India’s adoption of the S-400 put a strain on its relationship with Washington. In March 2021, then-Secretary of Defense Lloyd Austin warned Indian Defense Minister Rajnath Singh that New Delhi could face consequences for its purchase of the Russian S-400 air defense system.
The S-400 Is a Key Component of the Russia-India Partnership
Further supplies of the Triumf were among the topics discussed by Indian and Russian officials in Qingdao, China, on the sidelines of the recent Shanghai Cooperation Organization meeting of defense ministers.
“India is an exceptionally important strategic partner for us. It is a long-standing and trusted friend, including in the military and technological domains,” Russian Defense Minister Andrey Belousov told reporters after talks with Singh.
India remains the largest customer of Russian military hardware, despite New Delhi’s efforts to increase its domestic arms production and Western attempts to discourage Global South nations from doing business with the Kremlin.
The S-400 Was Crucial for India During Operation Sindoor
Even with the losses in Ukraine, India remains committed to the S-400, which The Times of India reported “played a crucial role during Operation Sindoor,” India’s recent air campaign against Pakistan. The Indian military claimed the Triumf intercepted multiple Pakistani missiles and drones, and even downed a surveillance aircraft that was operating deep within Pakistan.
Islamabad also claimed that it hit one of New Delhi’s S-400s with a missile fired from a JF-17 fighter. The Indian military has not confirmed the loss of the air defense platform, but if Pakistan’s claim is true, it would mark the first loss of an S-400 system in combat outside of Ukraine. Kyiv’s forces have successfully destroyed components of three S-400 batteries, with the most recent incident occurring on June 26, 2025.
Russia’s S-400 Air Defense System Is in High Demand Worldwide
Since its first entry into service in 2007, the S-400 has become one of Russia’s most high-profile combat platforms, earning comparisons to the American-made MIM-104 Patriot.
The development of the S-400 began as part of the S-300 modernization project. However, the Triumf was seen as a vast leap in performance and capabilities over earlier air defense systems, even though 70 to 80 percent of the technology employed in the initial S-400 design was taken and adapted from the S-300. Initially, this included missile storage containers, launchers, and radar. Each S-400 squadron consists of two missile batteries, armed with upwards of 128 missiles.
However, there are notable differences between the S-300 and S-400.
Whereas the S-300 was explicitly designed as a long-range air defense system, the S-400 is currently compatible with four missiles that fill a broad spectrum of operational categories: very long-range 40N6E (400 kilometers/250 miles), long-range 48N6 (250 kilometers/155 miles), medium-range 9M96e2 (120 kilometers/75 miles) and short-range 9m96e (40 kilometers/25 miles). The 40N6 missiles are the most capable, as they are designed to engage targets at a distance of up to 400 kilometers (250 miles) and at speeds of up to six times the speed of sound, from an altitude of up to 30 kilometers, under intensive enemy fire and jamming.
In the conflict in Ukraine, the S-400 has also been employed to strike ground targets, notably rocket artillery, while serving as an alternative to precision-guided missiles.
The Kremlin has claimed that the Triumf radar system, which utilizes three diverse arrays that broadcast across multiple frequency bands to track and target aerial threats, can even track the fifth-generation US-made F-22 Raptor air superiority fighter. This serves to highlight why NATO’s warning that the system is not a compatible platform with its Western-made fighter jets is a valid concern.
About the Author: Peter Suciu
Peter Suciu has contributed over 3,200 published pieces to more than four dozen magazines and websites over a thirty-year career in journalism. He regularly writes about military hardware, firearms history, cybersecurity, politics, and international affairs. Peter is also a Contributing Writer for Forbes and Clearance Jobs. He is based in Michigan. You can follow him on Twitter: @PeterSuciu. You can email the author: [email protected].
Image: Shutterstock / AjayTvm.
