Russian and U.S. officials have begun a third round of nuclear arms-control talks in the Austrian capital as the end of the 2010 New Strategic Arms Treaty (New START) looms.
The two-day meeting in Vienna is led by U.S. Special Presidential Envoy for Arms Control Marshall Billingslea and Russian Deputy Foreign Minister Sergei Ryabkov.
"The U.S. is prepared for a serious dialogue," Billingslea tweeted as he arrived.
The two powers are discussing their last remaining nuclear arms-control agreement, New START.
The bilateral treaty, which caps the number of deployed long-range nuclear warheads each country can have, expires in February.
The first two rounds of talks between the United States and Russia took place in June and July with no apparent breakthrough on a possible extension of the New START treaty.
The United States has urged China to join the negotiations -- a proposal rejected by Beijing.
"Open-minded professional dialogue is better than propagandistic rhetoric which prevailed in this area for a long time," Mikhail Ulyanov, the Russian ambassador to international organizations in Vienna, tweeted.