The U.S. ambassador to NATO says members of the alliance "stand united" ahead of high-stakes talks with Russia over the future of European security as concerns about a possible Russian invasion of Ukraine hang in the balance.
The Western military alliance's 30 members will meet with Russian officials at NATO headquarters in Brussels on January 12 to discuss Moscow's demand for security guarantees as well as the Kremlin's troop buildup near Ukraine.
Russia is demanding NATO commit to ending its eastward expansion and roll back its advances in Central and Eastern Europe since the 1990s.
"It has become crystal-clear that not a single ally inside the NATO alliance is willing to budge or negotiate anything as it relates to NATO's open-door policy," U.S. Ambassador to NATO Julianne Smith said on January 11.
"NATO is open and committed to a meaningful reciprocal dialogue with Russia," Smith said. "At the same time, we stand united to deter threats against NATO allies and further Russian aggression against our partners in Europe."
Russia has amassed nearly 100,000 troops near its border with Ukraine and in Ukraine's Russian-occupied Crimean Peninsula in what the United States has said could be a prelude to an invasion.
Western officials and analysts say Russia's buildup is an attempt to pressure the United States and European allies to make concessions.
On January 11, Russian forces staged live-fire exercises with tanks and about 3,000 troops near Russia's southern border with Ukraine.
Smith reiterated the U.S. call for Russia to de-escalate by withdrawing its troops and pursuing diplomacy.
SEE ALSO: Questions About Russia's Commitment To Diplomacy Persist After High-Stakes Talks With The U.S.NATO in 2008 committed to accepting Ukraine and Georgia, two former Soviet states that border Russia, into the alliance at an undetermined future date.
Russia has called Ukraine's membership in NATO a "red line." Many analysts say that Ukraine's membership in the alliance is at least a decade away.
The NATO-Russia Council meeting on January 12 follows bilateral talks between the United States and Russia in Geneva on January 10.
U.S. Deputy Secretary of State Wendy Sherman, who led those talks, briefed officials from NATO earlier in the day about her conversations with Russian Deputy Foreign Minister Sergei Ryabkov during eight hours of talks she described as "serious" and "businesslike."
"I briefed the North Atlantic Council on yesterday's discussions with Russia at the Strategic Stability Dialogue in Geneva," Sherman wrote on Twitter on January 11 after meeting with NATO Secretary-General Jens Stoltenberg and ambassadors from NATO member states.
"The United States is committed to working in lockstep with our Allies and partners to urge de-escalation and respond to the security crisis caused by Russia," she added.
SEE ALSO: U.S.-Russia Conclude 'Difficult' Geneva Talks On Ukraine, European SecurityDuring a call with media on January 11, Kremlin spokesman Dmitry Peskov said the U.S.-Russia talks were open and direct but did not lead to any progress on issues that Moscow deems urgent.
"We see no real reason to be optimistic so far," Peskov said.
The NATO-Russia Council talks are to be followed by a meeting of the Organization for Security and Cooperation in Europe (OSCE) on January 13 in Vienna. The United States, Russia, and Ukraine are all members of the OSCE.
Peskov said Russia would get a "clear picture" of where the United States stands with regards to its demands at the conclusion of all the talks this week in Europe.
Sherman said on January 10 that the United States and Russia would sit down following the OSCE meeting to discuss the next steps.
Peskov said there was "no deadline" for the talks, but "Russia's position is that we would not be satisfied with an endless dragging out of this process."
Meanwhile, Ukrainian Foreign Minister Dmytro Kuleba on January 11 praised "unity" with the West against what he called Russian "ultimatums."
Ukraine's Foreign Ministry said in a statement that Kuleba told U.S. Secretary of State Antony Blinken on January 11 that the Geneva talks proved "our strength lies in the unity and coherence of positions against...Russian ultimatums."
Kuleba also said the United States remains Kyiv's No. 1 security partner.
SEE ALSO: U.S. Will 'Respond Decisively' If Russia Invades Ukraine, Biden Tells ZelenskiyU.S. President Joe Biden and Putin held two phone calls in December, accompanied by a flurry of diplomacy involving officials from the United States, its European allies and Ukraine, and Russia ahead of the meetings this week.
Ryabkov commented after the Geneva talks that he had assured Sherman that U.S. and NATO concerns about Russia's military buildup on its border with Ukraine were unfounded.
Still, Sherman said in a separate tweet on January 11 that Washington's support for Kyiv was unwavering.
"We affirmed a unified @NATO approach toward Russia balancing deterrence and dialogue and stressed our unwavering support for Ukraine," she wrote.