US expectations that China will join nuclear arms control talks are unrealistic, Russia’s Deputy Foreign Minister Sergey Ryabkov said, noting the only way forward is bilateral dialogue between Moscow and Washington.

Ryabkov pointed out that he made that clear to US special envoy for arms control Marshall Billingslea as the two met in Vienna on Monday for negotiations on prolonging the New START Treaty, which expires in February.

“We quite thoroughly explained to them why counting on China joining [the negotiations] is unrealistic,” Ryabkov said, noting that Moscow will not pressure Beijing the way Washington wants it to as it respects China’s decision.

Bilateral dialogue between Russia and the US is “the optimal and, possibly, the only way forward at this stage” to preserve the landmark deal, which limits the number of nuclear launchers operated by the two countries, the deputy FM said.

However, he acknowledged that his efforts weren’t enough to make the US abandon its idea of including China in the process.

Washington has been insisting on including China in discussions of New START and the INF Treaty it ditched last year.

The Trump administration had invited Beijing’s representatives to Vienna, but China responded that it had “no intention” of getting involved in trilateral talks.

In an apparent attempt to shame Beijing, the American delegation made a staged photo before the beginning of the summit in the Austrian capital, which featured Chinese flags in front of empty seats in the conference room.

Billingslea than posted this image on his Twitter page, saying that “China is a no-show” and accusing it of “hiding behind #GreatWallofSecrecy on its crash nuclear build-up, and so many other things.”