President Trump with Russian President Vladimir Putin in Danang, Vietnam, on Nov. 11. (Mikhail Klimentyev/AFP/Getty Images)

TO APPRECIATE the significance of the Intermediate-Range Nuclear Forces Treaty, signed in 1987 by the Soviet Union and United States, just gaze up at the Pioneer and Pershing II missiles on display at the National Air and Space Museum in Washington. The Soviet missile looms nearly 55 feet tall, with a bulbous reentry vehicle for three nuclear warheads, and the more svelte U.S. missile, nearly 35 feet, with one warhead. These menacing weapons were at the center of an intense arms race in Europe in the late 1970s and early 1980s. Then it was reversed.

It was reversed by a treaty that was the first of the Cold War to eliminate a whole class of nuclear weapons, signed Dec. 8, 1987, in Washington by President Ronald Reagan and Soviet leader Mikhail Gorbachev, a hopeful time when both superpowers put trust in a binding and verifiable agreement to reduce the threat of nuclear war.

Now that trust is crumbling, and the reversal is being reversed. The United States and Russia seem to be returning to an arms race they halted a generation ago. Both sides claim they do not want this even as they let it happen. The treaty eliminated land-based missiles in Europe with ranges between about 310 and 3,420 miles, and their launchers; prohibited flight-testing and production of new missiles in the future; and included intrusive verification measures.

In 2014 and each year since, the State Department has informed Congress that Russia has developed and tested a ground-launched cruise missile with a range in violation of the treaty. Russia has denied it, and the details are still cloudy, but the charge appears to be based on testing of a new ground-launched cruise missile, the 9M729, that some say is now being deployed. At the same time, Russia has complained that aspects of the U.S. Aegis Ashore missile defense system could be in violation of the treaty; the United States has denied this. The treaty drafters envisioned a mechanism, the Special Verification Commission, for resolving disputes, and in November 2016, there was a meeting, without result.

The Trump administration announced in December, on the 30th anniversary of the treaty's signing, that "we are now pursuing economic and military measures intended to induce the Russian Federation to return to compliance." Congress declared in the National Defense Authorization Act signed by President Trump that Russia's actions "constitute a material breach of the treaty" and voted for $58 million to fund research on a new ground-based missile as a way to prod Moscow. President Vladimir Putin of Russia replied Dec. 14 that he believed the United States was preparing to withdraw from the treaty.

This environment of acrimony and denial is essentially leading to the breakdown of the INF Treaty and the start of a new missile race. Given all the other dangers of nuclear arms and proliferation these days, does it make sense for both Russia and the United States to wreck a model treaty that wiped out an entire class of dangerous missiles? No.