The finding was delivered to Congress and summarized in a statement by the State Department. It follows months of more hopeful US assessments that the two countries would be able to salvage cooperation on limiting strategic nuclear weapons despite high tensions over Russia's war on Ukraine.

Inspections of US 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 US-Russia committee overseeing implementation of the treaty last met in October 2021, but Russia then unilaterally suspended its cooperation with the treaty's inspection provisions in August 2022 to protest US support for Ukraine.

"Russia's refusal to facilitate inspection activities prevents the United States from exercising important rights under the treaty and threatens the viability of US-Russian nuclear arms control," the State Department said Tuesday.

The administration also blamed Russia for the two country's failure to resume talks required under the New START treaty.

Russia's Foreign Ministry said last August that it had told the US it was temporarily suspending on-site inspections required under the treaty. It said US sanctions imposed over Russia's February 2022 invasion of Ukraine had changed conditions between the two countries and claimed that the US was blocking Russians from carrying out their own inspections at US sites.

The State Department on Tuesday denied that the US was blocking inspections by the Russians.

It insisted the US-Russia nuclear arms control efforts were essential to the security of the US, its allies and the world at large.

"It is all the more important during times of tension when guardrails and clarity matter most," the State Department said.?