The United States and Russia meet Monday in Vienna for talks on their last major nuclear weapons agreement against a backdrop of growing tensions and differences over whether they see any value in arms control at all.
US President Donald Trump insists that China should be involved in the talks on New START, the treaty that caps US and Russian nuclear warheads, because he says up until now Beijing has had a free pass to do as it likes in developing weapon systems.
China has shown no sign of being interested, giving Washington fresh cause for complaint, although critics say the US finds that a useful stick with which to beat its growing rival.
The delegations made no statement when they arrived at 8:30am (0630 GMT) at the Niederoesterreich Palace in the Austrian capital where the talks are taking place.
Daryl Kimball, executive director of the Washington-based Arms Control Association, said the insistence on including China showed the Trump administration was not serious about an accord.