Russia wants Nato to remove all of its forces from Bulgaria, Romania and other ex-communist states in eastern Europe that joined the alliance after 1997, the foreign ministry said on Friday, underlining Moscow’s hardline position ahead of security talks with the US in Geneva.

Sergei Lavrov, Russia’s foreign minister, said in a written Q&A on the ministry’s website that Russia’s demands included “withdrawing foreign forces, equipment, and armaments and making other steps to return to the condition as of 1997”, when Nato began admitting former Warsaw Pact countries.

“That includes Bulgaria and Romania,” Lavrov said, adding that Russia’s demand was “core” and “deliberately worded as clearly as possible so as not to allow any dual interpretations”.

Bulgaria’s prime minister, Kiril Petkov, responded quickly, rebutting Lavrov. “Bulgaria is a sovereign country, which has made its choice long ago by becoming a NATO member,” he told parliament. “As such, we alone decide [how] to organise the defence of our country in coordination with our partners.”

Western officials say Russian president Vladimir Putin is closer than ever to launching a renewed invasion of Ukraine after amassing more than 106,000 troops close to its border in recent weeks. In Ukraine’s eastern Donbas border region more than 14,000 people have died in a slow-burning conflict since 2014.

The US has mounted a frantic diplomatic effort to de-escalate tensions and warned of “crippling” sanctions in case of any Russian aggression against Ukraine.

But western unity frayed this week after US president Joe Biden appeared to suggest a western response would depend on the scale of Russia’s intervention and French president Emmanuel Macron proposed separate European-led security talks with Moscow.

Biden later clarified his comments by saying that Russia would “pay a heavy price” in the event of any incursion.

Lavrov and Antony Blinken, US secretary of state, are holding talks on Moscow’s security demands in Geneva on Friday but both said they did not expect a breakthrough.

Blinken said at the start of the talks: “I do hope and expect that we can test whether the path of diplomacy, of dialogue, remains open. We’re committed to walking that path, to resolving our differences peacefully and I hope to test that proposition today.”

But he said the US and its allies were committed, “if that proves impossible, and Russia decides to pursue aggression against Ukraine, to a united, swift and severe response”.

Lavrov said Russia did not “expect a breakthrough at these negotiations either” and added that he expected a written US response to Moscow’s draft security proposals, “which are extremely concrete and we await equally concrete answers”.

The US and its European allies have said Russia’s demands that Nato pledge never to admit Ukraine and to roll back the alliance’s eastward expansion — which would essentially rewrite the post-cold war security order — are unacceptable.

Macron said on Wednesday that France was ready to send troops to Romania if Nato decided to beef up its presence there. Nato members are discussing troop deployments in the Black Sea region under its “enhanced forward presence” missions, akin to those in Poland and the Baltic states following Russia’s annexation of Crimea in 2014.

Putin has vowed an unspecified “military-technical response” if the west does not agree to Russia’s draft security proposals.