BRUSSELS (AP) — NATO called Friday on Russia to respect the only treaty it has with the United States aimed at keeping a lid on nuclear weapons expansion and urged Moscow to allow on-the-ground inspections of military sites to resume.

The so-called New START Treaty was signed by Russia and the U.S. in 2010. It caps at 1,550 the number of long-range nuclear warheads they can deploy and limits the use of missiles that can carry atomic weapons. It allows short-notice inspections of each other’s nuclear bases and support facilities.

“We note with concern that Russia has failed to comply with legally-binding obligations under the New START Treaty,” NATO ambassadors said in a statement. The 30-nation U.S.-led military alliance supports the treaty and believes that it helps to limit the expansion of nuclear forces.

The envoys said that Russia’s refusal to hold consultations or to allow U.S. inspections since last August “prevents the United States from exercising important rights under the Treaty, and undermines the United States’ ability to adequately verify Russian compliance with the Treaty’s central limits.”

“We call on Russia to fulfil its obligations under the Treaty by facilitating New START inspections on Russian territory, and by returning to participation in the Treaty’s implementation body,” the forum in which the two sides could consult, NATO said.

President Vladimir Putin has repeatedly ramped up his nuclear rhetoric since he ordered Russian troops into Ukraine almost a year ago, raising concern among Western allies and the public over whether he might actually use such weapons.

The U.S.-Russia committee formed under the treaty last met in October 2021, but Russia unilaterally suspended its cooperation with the pact’s inspection provisions in August 2022 to protest U.S. support for Ukraine.

Inspections of U.S. and Russian military sites under the New START treaty were paused by both sides because of the spread of the coronavirus in March 2020.

The U.S. State Department warned Tuesday that “Russia’s refusal to facilitate inspection activities prevents the United States from exercising important rights under the treaty and threatens the viability of U.S.-Russian nuclear arms control.”