US-Russia arms control talks started in Vienna on Monday as the fate of the last nuclear arms control treaty between the two powers hangs in the balance. Russia has offered to extend the New START treaty, which is set to expire in February 2021, but the Trump administration has not agreed to the extension, calling for China to get involved in a new deal.

The US formally invited China to attend the talks, but Beijing has been clear in saying they have no interest in trilateral arms control agreements since China's nuclear arsenal is much smaller than the US and Russia's. President Trump's lead envoy for the talks continues to focus the conversation on China.

US Envoy for Arms Control Marshall Billingslea shared a picture from Vienna on Twitter of empty chairs with Chinese flags around them and said China was a "no-show." Arms control advocates fear the Trump administration's insistence on including China in the deal is only to use Beijing's unwillingness to participate as an excuse to let the New START expire.

In another Tweet, Billingslea said the talks with his Russian counterpart went well. "First round of Vienna talks very positive. Detailed discussions on full-range of nuclear topics. Technical working groups launched. Agreement in principle on second round," Billingslea said.