Russia wants the "withdrawal of foreign forces, hardware and arms" from countries that were not NATO members before 1997, the foreign ministry said in a statement.

"These include Bulgaria and Romania," the statement added, singling out the two former Warsaw Pact allies that joined NATO in 2004.

US Secretary of State Antony Blinken and Russia's Foreign Minister Sergei Lavrov met in Geneva on Friday for a new round of security talks to ease soaring tensions between Russia and the West over Ukraine.

Western countries accuse Russia of amassing tens of thousands of troops on the border with Ukraine and planning to invade the ex-Soviet country.

Moscow denies the claims and last month presented Washington and NATO with proposals aimed at curbing the eastward expansion of the military alliance in exchange for a de-escalation of tensions.

Russia's security demands included that NATO must not admit any new members -- in particular Ukraine and Georgia -- and a guarantee that the United States will not establish new military bases in former Soviet countries.

Following their meeting on Friday, Lavrov said Russia was expecting to receive a written response from Washington next week.

There are around 1,000 US and 140 Italian troops stationed in Romania on a rotational basis as well as several dozen Polish troops.

On Thursday, Romania said it was ready to welcome more American troops on its soil.

Bulgaria has an agreement with the United States for the deployment of up to 5,000 troops on rotation.

NATO battle groups have around 5,000 troops in total across the Baltics and Poland.

The alliance is also considering whether to boost its presence around the Black Sea, for example in Romania and Bulgaria, with similar deployments.

Under NATO's umbrella, the United States has also deployed a ballistic missile defence site to Romania and is constructing one in Poland.