MOSCOW (AP) — Russia says Ukraine’s deal to buy U.S.-made nuclear fuel for its Soviet-built reactors could trigger a nuclear accident.

Prime Minister Arseniy Yatsenyuk of Ukraine announced Tuesday that his nation has reached a deal on nuclear fuel deliveries with Westinghouse to reduce dependence on Russian supplies.

Russia’s Foreign Ministry deplored the move as a “dangerous experiment that threatens safety and health of the Ukrainian citizens and peoples of Europe.” It said nuclear fuel produced by the U.S. company doesn’t quite fit Soviet-built nuclear reactors that Ukraine has.

The ministry said Ukrainian authorities must take a responsible approach to nuclear safety, or risk disasters such as the 1986 Chernobyl one, which was a result of a flawed Soviet reactor design coupled with serious mistakes made by the plant operators.

In a statement Tuesday, Westinghouse said it “has been working in the Ukrainian market since 2003, and brings diversification of suppliers, global best practices and technology to the Ukraine market. Westinghouse fuel is currently operating safely and efficiently at the South Ukraine Nuclear Power Plant without any defects in performance.”