U.S., Ukraine Collaborate on S-300 Modernization and New Missile Development

The United States and Ukraine are jointly working on modernizing older missiles for the S-300 air defense system or developing a newer version with enhanced capabilities.

Robert Hamilton, a retired U.S. Army colonel and president of the Delphi Global Research Center, told PBS NewsHour about the effort.

According to him, the upgraded system is expected to become operational closer to the end of 2026.

“Joint U.S.-Ukrainian efforts are underway to modernize older S-300 missiles or develop a newer variant that would improve their capabilities,” Hamilton said.

He noted that the effort involves the production of 100 or a couple of hundred surface-to-air missiles per year.

Back in September 2024, then-U.S. Secretary of Defense Lloyd Austin said at a meeting of the Ukraine Defense Contact Group in Ramstein that the United States was working with Ukraine on developing a ‘replacement’ for Soviet-era S-300 air defense systems and R-27 air-to-air missiles.

“With the support of several European companies, the United States is working together with Ukraine to develop and manufacture a replacement for the S-300-class surface-to-air missile system, as well as the R-27 air-to-air missile,” Austin said.

He did not specify what exactly is meant by ‘replacement’ in the context of the air defense system.

At the beginning of Russia’s full-scale invasion, Ukraine had approximately 25–30 S-300PT/PS battalions in varying states of combat readiness.

Over the years of the war, Ukraine’s stockpiles of missiles for these systems have been depleted, and the country now relies on supplies of Western air defense systems and missiles for them amid continued large-scale Russian missile attacks.

In December 2025, the Norwegian government announced the allocation of funds for the procurement of anti-aircraft missiles for Ukraine’s S-300 air defense systems as part of military assistance.

Shortly before that, it became known that Ukraine’s defense industry was working on the localization of missiles for the S-300 and S-400 air defense systems, combined with a European radar.