Slovakia said Wednesday it would buy nine Black Hawk military helicopters from the United States for $261 million (236 million euros), as it revamps its armed forces amid the conflict in neighbouring Ukraine.

The NATO member is following in the steps of Poland and the Baltic states, which have upped defence spending because of security concerns over the Kremlin's territorial ambitions.

Moscow annexed the Crimean peninsula from Ukraine last year and is accused by the West of sending arms and troops to aid pro-Russian separatists battling government troops in Ukraine's east -- a charge Russia denies.

Delivery of the UH-60 Black Hawk choppers is expected between 2016 and 2019, Slovak Defence Minister Martin Glvac told reporters.

Made by Sikorsky Aircraft, the helicopters will replace Russian Mi-17 aircraft that is reaching the end of its life cycle. The contract will also involve pilot training and equipment maintenance.