Russia has warned the US and Nato to make concessions or face a worsening security situation in Europe, as it downplayed the potential for progress in talks between Moscow and Washington aimed at averting an invasion of Ukraine.

Russian and US officials are meeting on Monday in Geneva for high-stakes negotiations on Ukraine and wider European defence. The talks were prompted by Russia’s deployment of about 100,000 troops close to its border with Ukraine and its warnings of military action if the west ignores demands for new guarantees that would reshape Europe’s security architecture.

Sergei Ryabkov, Russia’s deputy foreign minister and lead negotiator in Geneva, said Russia would not yield on its demand for Nato to never make Ukraine a member, a pledge the US and the military alliance has already ruled out.

“Now the other side must show flexibility. If they are unable to do this, then they will face a worsening situation in their own security,” he told Russian state news agency Ria. “I have rather pessimistic forecasts in this regard, but we will persistently explain that without solving this key task, a productive dialogue will not work.”

The talks are the first in a series of diplomatic meetings this week aimed at deescalating the situation in Ukraine. Nato’s secretary-general has told the Financial Times that the alliance hopes for “co-operation” from Moscow but is prepared for possible conflict.

Ryabkov leads a delegation that will spend Monday locked in talks with a US delegation led by Wendy Sherman, deputy secretary of state.

“The US will listen to Russia’s concerns and share our own, but we have been clear we will not discuss European security without our allies and partners,” Sherman said as the talks began.