Russia’s suspension last week of the world’s biggest bilateral nuclear-weapons treaty is not official yet and Moscow was still talking to the State Department about the treaty as of Monday, a senior agency official said.

“The suspension hasn’t been officially effected yet, in the sense that we’re still receiving notifications as recently as today under the treaty,” said Mallory Stewart, assistant secretary of state at the Bureau of Arms Control, Verification, and Compliance, in an hour-and-15-minute appearance at the Brookings Institution think tank in Washington Monday on morning. “But we expect that as soon as that suspension has been formalized that those will stop.”

The writing is on the wall. Vladimir Putin, the Russian president, told Russia’s legislature, the Duma, last week that the U.S. would not be allowed to inspect Russian nuclear weapons facilities, even though the 2011 New START treaty requires it.

“We’re trying to follow up with them to truly understand what else could be included in the suspension and what could be continued, but right now we expect it will just be the launch notifications” for tests of intercontinental ballistic missiles under the Ballistic Missile Launch Notification Agreement of 1988, Stewart said Monday at Brookings.

The U.S. and Russia routinely exchange information under New START, including about the number of deployed warheads and launchers each country has. 

Stewart’s 17-minute prepared remarks on Monday at the think tank, open to the press and the public for the occasion, were largely a continuation of the unofficial public volley between Moscow and Washington about the treaty. 

Stewart summarized and repeated U.S. talking points that filtered out in media reports and official appearances last week, recounting Russia’s refusal since June 2022 to allow U.S. inspectors access to Russian nuclear-weapon sites and attempting to rebut a Russian foreign ministry statement last week that the U.S. violated New START by refusing to confirm that certain U.S. submarine ballistic missile launchers and heavy bombers had been modified to such an extent that they should not longer be counted as launchers under the treaty. 

New START limits Washington and Moscow to 1,500 deployed strategic warheads on no more than 700 intercontinental ballistic missiles, submarine-launched ballistic missiles, and heavy bombers. A heavy bomber counts as a single launcher under the treaty. 

The U.S. and Russia suspended New START inspections during the COVID-19 pandemic, which broke out in early 2020, but Stewart said the U.S. and Russia could have safely resumed in-person inspections as soon as last summer.

In his speech to Russian government officials last week, Putin said that the U.S. only wants to inspect Russian nuclear facilities so that Washington can pass on information about those facilities to Ukraine, which intends to attack the facilities. 

In December, media around the world reported that Ukraine had attacked Russia’s Engels Air Force Base using uncrewed aerial vehicles. The Russian base, widely reported to be home to nuclear-capable Russian bombers that can also launch convention missiles, is near the banks of the Volga River by the Russian city of Saratov, about 450 miles southeast by road from Moscow and roughly 760 miles east by road from Kyiv, the Ukrainian capital.

Ukraine did not take credit for the December attacks on Engels.