The last remaining treaty that limits Russian and U.S. nuclear weapons was already in grave peril before President Vladimir Putin announced on Tuesday that Moscow was suspending its participation.

Now it may be beyond repair, raising the risk of a new arms race — in parallel with the war in Ukraine — in which neither side can rely on the stable, predictable framework that successive nuclear accords have provided for more than 50 years.

Security analysts said that could hugely complicate the delicate calculus that underpins mutual deterrence between the two countries, while also spurring other powers such as China, India and Pakistan to build up their nuclear arsenals.