Over 30 years ago, President Ronald Reagan and I signed in Washington the United States-Soviet Treaty on the elimination of intermediate- and shorter-range missiles. For the first time in history, two classes of nuclear weapons were to be eliminated and destroyed.

This was a first step. It was followed in 1991 by the Strategic Arms Reduction Treaty, which the Soviet Union signed with President George H.W. Bush, our agreement on radical cuts in tactical nuclear arms, and the New Start Treaty, signed by the presidents of Russia and the United States in 2010.

There are still too many nuclear weapons in the world, but the American and Russian arsenals are now a fraction of what they were during the Cold War. At the Nuclear Nonproliferation Review Conference in 2015, Russia and the United States reported to the international community that 85 percent of those arsenals had been decommissioned and, for the most part, destroyed.

Today, this tremendous accomplishment, of which our two nations can be rightfully proud, is in jeopardy. President Trump announced last week the United States’ plan to withdraw from the Intermediate-range Nuclear Forces Treaty and his country’s intention to build up nuclear arms.