Senior diplomats from the world's two biggest nuclear powers have been trying to strike a new arms control deal. The US wants an unwilling China to sign up to a new trilateral nuclear arms control deal.
Senior Russian and US diplomats held arms control talks in Vienna on Monday as they race to replace a decade-old nuclear weapons deal that expires in eight months.
The New START agreement is the last remaining nuclear arms control deal between the new nations, but is due to expire in February.
The talks at the Palais Niederösterreich in the Austrian capital were expected to continue until Tuesday.
However, observers have little hope for success as US negotiators hope to replace the bilateral agreement with a trilateral deal that brings China into the fold, despite it having clearly signaled unwillingness.
US negotiators criticized China for not attending the meeting, with chief envoy Marshall Billingslea sharing a photo of an empty place prepared for China.
However, he said negotiations would continue with Russia.
The US and Russia hold an estimated 90% of the world's nuclear weapons, however China has been building up its stock in recent years.
Russian security expert Dmitry Suslov told state media ahead that the US was unlikely to extend the current agreement without China's participation.
Deputy Foreign Minister Sergei Ryabkov told reporters ahead of the meeting: "Let's see, let's see. We are always very hopeful."
New START limits each country to 800 nuclear missile launchers and 1,550 operational nuclear warheads. It can be extended for up to five years if both sides agree.
The Stockholm International Peace Research Institute estimates that Russia has 6,375 nuclear warheads, including those that are not deployed, and the United States has 5,800. It says China has 320 warheads.
aw/msh (AFP, Reuters, dpa)