The improvement of security for nuclear materials like weapons-grade uranium and plutonium, as well as reductions in nuclear weapons arsenals, brought Russia and the United States together over the past 25 years. But the common ground has been disappearing as President Vladi­mir Putin takes a more confrontational stance toward the United States and tensions deepen over Russian actions in Syria and Ukraine.

When it was signed in 1987, the Intermediate-Range Nuclear Forces treaty was the first to wipe out a whole class of nuclear arms. Russia inherited the obligations of the Soviet Union to eliminate ground-based ballistic and cruise missiles with a range between about 300 and 3,400 miles. But the United States says Russia is quietly violating the treaty with a new ground-launched cruise missile, and recent reports suggest Russia may be making more of them. Russia has denied being in violation. The Obama administration has now asked for a rare meeting of a special commission established to hash out compliance issues. A violation of this magnitude, if true, cannot be overlooked; a failure to settle the issue could weaken the treaty.

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