Nuclear experts and peace advocates on Friday shared their heightened concerns about a new arms race as the Trump administration officially withdrew from a landmark treaty with Russia that was signed by former U.S. President Ronald Reagan and Soviet leader Mikhail Gorbachev in 1987.

“By walking away from the INF Treaty, Donald Trump and Vladimir Putin have further undermined the Non-Proliferation Treaty (NPT) and put the world at heightened risk of nuclear weapons use and war.”
—ICANDespite warnings about how ditching the Intermediate-Range Nuclear Forces (INF) Treaty could impact global security, U.S. President Donald Trump suspended U.S. obligations under the decades-old deal in February, notifying Moscow that it had six months to destroy weapons that Washington and NATO claim violate the agreement.

Russian President Vladimir Putin quickly followed suit, suspending his country’s commitments under the Cold War-era treaty, which banned either party from possessing nuclear and non-nuclear missiles with ranges between 310 and 3,400 miles, excluding those launched from sea.

U.S. Secretary of State Mike Pompeo confirmed in a statement Friday that the United States has withdrawn from the deal “because Russia failed to return to full and verified compliance through the destruction of its non-compliant missile system—the SSC-8 or 9M729 ground-launched, intermediate-range cruise missile.”

Pompeo declared Russia “solely responsible for the treaty’s demise” and noted that Washington first raised concerns with Moscow about the weapon in question in 2013, under the Obama administration. As Pompeo put it, “Russia subsequently and systematically rebuffed six years of U.S. efforts seeking Russia’s return to compliance.”

Moscow maintains its cruise missiles do not violate the treaty but that the U.S. missile defense systems in Europe do—a charge that Washington has denied. In a statement to Russian state-run Ria Novosti news agency reported by BBC News Friday, Russia’s foreign ministry confirmed that the treaty was “formally dead.”

“The risk of nuclear weapons use is already unacceptably and unnecessarily high. The death of the INF Treaty, without any plan in evidence to compensate for the deterioration of arms control, will only accelerate our downward spiral into nuclear chaos and potential catastrophe,” warned Jon Wolfsthal, director of the Nuclear Crisis Group, an international task force of top former nuclear commanders, senior military officials, and diplomats that came out of the disarmament campaign Global Zero.

The International Campaign to Abolish Nuclear Weapons (ICAN) said in a statement (pdf) that it “deplores the irresponsible destruction” of the agreement and “by walking away from the INF Treaty, Donald Trump and Vladimir Putin have further undermined the Non-Proliferation Treaty (NPT) and put the world at heightened risk of nuclear weapons use and war.”

ICAN—which was awarded the 2017 Nobel Peace Prize for its work to advance nuclear disarmament—urged the United States and Russia to pursue urgent talks to restore compliance and fully implement the INF Treaty, scale back their respective nuclear arsenals, and “pave the way for nuclear-free security by joining the U.N.’s multilateral Treaty on the Prohibition of Nuclear Weapons (TPNW), which was negotiated and adopted by over 122 nations at the U.N. General Assembly in 2017.”