The White House's top arms control official on Wednesday said US cooperation with Russia on agreements limiting nuclear arsenals would survive the worst East-West tensions in years sparked by Ukraine.
Elizabeth Sherwood-Randall said that US and Russian officials were even now working "effectively" together to prepare for a nuclear security summit in The Hague later this month which President Barack Obama will attend.
"We expect that the Russians will continue to abide by the arms control agreements that they have reached with us," said Sherwood-Randall, the White House Coordinator for Defense Policy, Countering Weapons of Mass Destruction, and Arms Control.
"These are in our mutual interest and we see no reason that tensions that exist over Ukraine should in any way obstruct the path towards fulfilling the commitments that we have made with the Russians to reduce nuclear weapons on both sides," she said at an event sponsored by National Journal in Washington.
As part of its earlier "reset" of relations with Russia, the Obama administration concluded a new Strategic Arms Reduction Treaty that limits both sides to 1,550 warheads and puts caps on the numbers of deployed intercontinental ballistic nuclear missiles and other launch vehicles.
The treaty includes verification mechanisms that include on-site inspections, data exchanges and other notifications so that each side can have confidence the other is complying with the terms of the pact.
The White House had hoped to follow on from the treaty with Russia to make further arms reductions in line with Obama's core counter-proliferation strategy, but those aspirations fell foul of worsening relations since Vladimir Putin's return to the Russian presidency.
The Obama administration, while vigorously condemning Russia's incursion into Crimea, has sought to insulate the wider US-Russia relationship, already rocky, from more permanent damage.
Officials argue that nuclear cooperation, along with common approaches to the Iranian nuclear issue, are two areas where it is in Russia's own national interest not to thwart US foreign policy.
That theory is likely to be put to the test if the White House goes ahead in the coming days with imposing meaningful sanctions on the Russian government and top officials over the Ukraine crisis.