Want smart analysis of the most important news in your inbox every weekday, along with other global reads, interesting ideas and opinions? Sign up for the Today’s WorldView newsletter.

A nonproliferation pact that underpinned three decades of global security collapsed on Friday. In 1987, the United States and the Soviet Union agreed to the Intermediate-Range Nuclear Forces Treaty, which led to the removal of more than 2,600 U.S. and Soviet nuclear and conventional ballistic missiles — specifically, ground-based weapons systems with ranges between 500 and 5,500 kilometers (310 and 3,417 miles). That proximate distance, and the fact that they could hit their targets within 10 minutes, made such missiles the source of constant miscalculation fears during the Cold War era.

The landmark agreement, backed by a verification process and inspections on both sides, effectively eliminated an entire class of nuclear weapons. It lifted the veil of permanent nuclear threat that hung over Europe. It also launched a lengthy subsequent process in which both Washington and Moscow reduced their nuclear arsenals.

Under President Trump, the clock is being dialed back. In February, the Trump administration gave notice that it would be exiting the INF Treaty in six months, citing long-standing U.S. complaints that Russia was violating the treaty’s terms with the development of a new land-based, nuclear-capable cruise missile. The Russians long denied the existence of the missile but now claim its range is under 500 kilometers (310 miles).

In any event, Moscow put up little fuss about exiting the agreement, seemingly content to let it expire. Officials in both countries felt handcuffed by the pact. Russia watched with wariness every time the United States deployed a new missile system with allies in Europe and Asia. Hawks in Washington, not least White House national security adviser John Bolton, saw the treaty as an anachronism that constrained American strategic options but did not affect a rising power such as China.

On Friday, Secretary of State Mike Pompeo tweeted, “The U.S. gave Russia six months to return to compliance with the Intermediate-Range Nuclear Forces Treaty. Russia refused, so the treaty ends today. The U.S. will not remain party to a treaty when others violate it. Russia bears sole responsibility.”

In a statement issued by the Russian Foreign Ministry, Moscow blamed Washington. As reported for The Post by Matthew Bodner in Moscow, the ministry accused the United States of intentionally undermining the treaty to justify the development and deployment of weapons once banned by the agreement. The statement pointed to past U.S. actions to support the claim, namely the Bush administration’s to unilaterally withdraw from the 1972 Anti-Ballistic Missile Treaty (ABM) in 2002 -- notice of which was, as was the case with INF, delivered personally to the Kremlin by John Bolton.

“The denunciation of the INF Treaty confirms that the US is set on destroying all international agreements that do not suit them for one reason or another,” the statement said. “This will lead to the dismantling of the existing arms control regime.”

The ministry’s statement again denied Washington’s accusations that Russia stands in violation of the treaty, and called for the U.S. to pledge it will not deploy weapons once banned by INF. The ministry noted that Russia has already announced a moratorium on deploying such weapons, “if we have them,” if the U.S. does not deploy them first. However, a number of Russian officials in recent weeks, including Deputy Foreign Minister Sergei Ryabkov -- Russia’s point-man on arms control -- have stated that Russia will mirror any deployments.

Leonid Slutsky, chairman of the Russian State Duma’s foreign affairs committee, upped the ante on Friday when he said the deployment of U.S. short- and medium-range missiles to Eastern and Central Europe is a serious threat to Russian national security. “Their flight time from Poland or the Baltic states is so short (about four minutes),” Slutsky was quoted as saying by Interfax, “that in this case Moscow will have to adopt a doctrine of pre-emptive strike.” Slutsky said this creates a significantly higher risk for nuclear exchange to be sparked “by mistake,” and called upon both sides to agree that such weapons will not be deployed in Europe. The State Duma’s defense committee chairman, Vladimir Shamanov, said of the U.S. withdrawal: “Let them quit. We have a response ready.”

Analysts reckon a new arms race is possibly in the offing. “Now that the treaty is over, we will see the development and deployment of new weapons,” Russian military analyst Pavel Felgenhauer told AFP, referring to the Kremlin’s next steps. The United States also is believed to be developing at least three new types of medium-range missiles — all of them intended to carry conventional warheads.

In an emailed memo, Jan Techau of the German Marshall Fund warned that the collapse of the INF Treaty was “the most visible proof” of the shifting geopolitical winds. “Washington calculated that in order to regain strategic parity with China in this field, it was worth sacrificing European stability,” Techau said. “As understandable as this is at the global level, for Europe it is a tragedy.”

Michael Birnbaum, the Brussels bureau chief for The Washington Post, explained to Today’s WorldView that European officials have moved beyond that sense of tragedy: “Within NATO, diplomats have finished mourning the demise of the treaty — all NATO members backed Trump’s decision to pull out — and have moved on to what to do to respond to the new situation. But many of Europe’s senior security policymakers grew up during the searing battles in the 1970s and 1980s about whether the United States should station medium-range nuclear missiles on European soil, and there is little appetite for a return to that era. Few want American medium-range nuclear weapons back on the continent.

“There is more of a debate about whether NATO nations need to ramp up their conventional missile defense so that it could protect against Russian threats. The United States has built missile defense systems in Romania and Poland, but they are designed to counter Iranian missiles, not Russian ones. Not all European countries would back overhauling them to defend against Russia as well.

“For now, NATO’s focus is on strengthening already existing efforts to defend Europe against Russia. That means improving the alliance’s ability to speed troops across Europe in case they need to deploy to countries that border Russia. It could also mean stepping up military exercises that take place in Eastern Europe nearly all the time.”

The end of the INF Treaty also paves the way for a broader unraveling. Bolton recently signaled that he also wants to end the Obama-era New START (Strategic Arms Reduction Treaty), which expires in 2021. Another historic agreement, it limited the number of strategic nuclear warheads deployed by the United States and Russia. Similar to their grievances with the INF agreement, Bolton and his ilk argue that New START is insufficient for the present moment and complain that it did not include short-range or tactical nuclear weapons — no matter that the treaty was not intended to address those sorts of capabilities.

Critics see these arguments as a smokescreen masking a militarist bent. “Key to these nuclear warfighting mindsets is the idea of ‘escalation dominance,’ where one side thinks it can use nuclear weapons but somehow prevent the other side from doing the same,” wrote arms control experts Bruce Blair and Jon Wolfsthal. “This conceit increasingly drives U.S. nuclear policy. President Trump and his advisers have strongly embraced this risky set of policies and seek new, so-called ‘low-yield’ nuclear weapons to make these threats easier to carry out.”

At the core of this thinking, Blair and Wolfsthal suggest, are “dangerous fantasies” that the United States could use a nuclear weapon against another nuclear-armed country without provoking a nuclear counterattack. On the debate stage this week, a handful of Democratic presidential candidates voiced their support for a “no first use” policy that would, by their calculations, lessen the risk of an actual nuclear war. But the world isn’t waiting for the United States to drastically change its present course in 2021.

“There is a very real risk that the whole security architecture around nuclear non-proliferation that was built up during the decades of superpower confrontation may collapse, through neglect, miscalculation and ill-founded threat analysis,” former U.N. secretary general Ban Ki-moon said in a statement.

In an interview with Voice of America, George Shultz, the U.S. secretary of state who was instrumental in negotiating the 1987 INF Treaty, lamented the world’s growing amnesia over the threat posed by nuclear weapons. “When something like the INF goes down the drain almost like nothing, it shows you the degree to which people have forgotten the power of these weapons,” Shultz said. “One day it’ll be too late.”

Want smart analysis of the most important news in your inbox every weekday, along with other global reads, interesting ideas and opinions? Sign up for the Today’s WorldView newsletter.