Donald Trump says the United States will pull out of the 1987 Intermediate-range Nuclear Forces (INF) treaty with Russia. The treaty has kept Europe free of U.S. and Soviet/Russian nuclear missiles for thirty years.

The treaty bans ground launch nuclear missiles with ranges from 500 km to 5,500 km. It eliminated nearly 2,700 short- and medium-range weapons.

Under Trump and National Security Adviser John Bolton, the U.S. is concerned that the treaty ties its hands in a strategic rivalry with China in the Pacific. It also alleges that Russia is violating the terms of the agreement with its development and deployment of a new cruise missile.

“This is the most severe crisis in nuclear arms control since the 1980s,” said Malcolm Chalmers, the deputy director general of the Royal United Services Institute. “If the INF treaty collapses, and with the New Start treaty on strategic arms due to expire in 2021, the world could be left without any limits on the nuclear arsenals of nuclear states for the first time since 1972.”

Speaking to reporters in Nevada, Trump said: “Russia has violated the agreement. They’ve been violating it for many years and I don’t know why President Obama didn’t negotiate or pull out.

“We’re not going to let them violate a nuclear agreement and do weapons and we’re not allowed to. We’re the ones that have stayed in the agreement and we’ve honoured the agreement but Russia has not unfortunately honoured the agreement so we’re going to terminate the agreement, we’re going to pull out.”

Asked to clarify, the president said: “Unless Russia comes to us and China comes to us and they all come to us and they say, ‘Let’s all of us get smart and let’s none of us develop those weapons,’ but if Russia’s doing it and if China’s doing it and we’re adhering to the agreement, that’s unacceptable. So we have a tremendous amount of money to play with with our military.”

Jeffrey Lewis, the director of the East Asia nonproliferation program at the Middlebury Institute of International Studies at Monterey, said: “This is a colossal mistake. Russia gets to violate the treaty and Trump takes the blame.

“I doubt very much that the US will deploy much that would have been prohibited by the treaty. Russia, though, will go gangbusters.”