NATO members announced they would halt operations in retaliation to Russia’s decision on Tuesday to withdraw from the Treaty on Conventional Armed Forces in Europe, a significant post-Cold War accord.

Russia formally withdrew from the security treaty, which restricted important categories of conventional armed forces, and accused the US of eroding security established after the Cold War by expanding NATO.

“Allies condemn Russia’s decision to withdraw from the Treaty on Conventional Armed Forces in Europe (CFE), and its war of aggression against Ukraine which is contrary to the Treaty’s objectives,” NATO said in a statement.

The Russian move was its latest action that systematically undermined Euro-Atlantic security, it said.

“Therefore, as a consequence, Allied States Parties intend to suspend the operation of the CFE Treaty for as long as necessary, in accordance with their rights under international law. This is a decision fully supported by all NATO Allies.”

The United States said it would suspend treaty obligations effective Dec. 7.

Russia’s war against Ukraine and its withdrawal from the treaty “fundamentally altered” circumstances related to it and transformed participants’ obligations, White House national security adviser Jake Sullivan said.

Russia suspended participation in the treaty in 2007 and halted active participation in 2015.