Russia has suspended a key Cold War arms control treaty in part to protest U.S. plans to build a missile defense system in Poland and the Czech Republic. The 1990 Conventional Forces in Europe Treaty limits the number of heavy weapons deployed between the Atlantic Ocean and the Urals Mountains.

Poland’s deputy foreign minister, Witold Waszczykowski: “The CFE is one of the foundations of the situation which was created after the end of the Cold War. And we of course would like to keep it, this treaty, of course with some amendments, with some modification which were discussed and was implemented some years ago. But of course we wouldn’t like to pull out from the treaty. We wouldn’t like Russia to pull out from this treaty.”

Russia’s decision comes five years after the Bush administration withdrew from the Anti-Ballistic Missile Treaty.