MOSCOW (AP) -- Moscow and Washington took uncompromising stands Tuesday ahead of more talks amid a Russian troop buildup near Ukraine, with the U.S. rebuffing a demand to halt NATO expansion and the Kremlin saying it will quickly see if it's worthwhile to even keep negotiating.
At Monday's talks in Geneva, Russia insisted on guarantees precluding NATO's expansion to Ukraine and other ex-Soviet nations and demanded to roll back the military alliance's deployments in Eastern Europe. The U.S. firmly rejected the demands as a nonstarter.
The U.S. envoy to NATO set a tough tone for the next talks with Moscow, ruling out any concessions on the alliance's eastward expansion.
"We will not allow anyone to slam NATO's open-door policy shut," U.S. Ambassador Julianne Smith said.
Kremlin spokesman Dmitry Peskov described the Geneva talks as "open, comprehensive and direct," but emphasized Moscow wants quick results.
"We see no significant reason for optimism," he told reporters.
Peskov said Russia-NATO talks in Brussels today and a meeting of the Organization for Security and Cooperation in Europe in Vienna on Thursday would show whether further negotiations are worthwhile.
"It will become clear in what direction and how to proceed and if it makes sense," he said. "We absolutely wouldn't accept dragging this process out endlessly."
Smith said "not a single ally inside the NATO alliance is willing to budge or negotiate anything as it relates to NATO's open-door policy."
"We stand firm in pushing back on security proposals that are simply nonstarters," she told reporters. "There's widespread unity and consensus across the alliance on the challenge that sits before us."
The U.S. estimated Russia has massed about 100,000 troops near Ukraine, a buildup that has stoked fears of an invasion. Moscow said it has no plans to attack and rejects Washington's demand to pull back its forces, saying it has the right to deploy them wherever necessary.
President Vladimir Putin has warned Moscow would take unspecified "military-technical measures" if the U.S. and its allies don't meet its demands. He spoke with members of his Security Council, saying he wanted to discuss unspecified issues related to security and infrastructure in border areas.
White House press secretary Jen Psaki said it was "too early to tell whether the Russians are serious about the path to diplomacy or not," or whether they will use the talks as a "pretext to claim that diplomacy couldn't possibly work" and move forward with an invasion.
Psaki sidestepped questions about whether the U.S. agreed the Geneva talks did not provide reason for greater optimism. She noted, however, they had included discussions about the placement of missiles in Europe and reciprocal limits on military exercises.
"There are a range of discussions that can be a part of a diplomatic path, but ultimately it's up to the Russians to determine about whether they're going to take a serious approach," she said.
Deputy Foreign Minister Sergei Ryabkov, who led the Russian delegation in Geneva, said afterward it would be hard to make any progress on other issues if the U.S. and its allies stonewall Moscow's demand for guarantees precluding NATO's expansion.
The U.S. and its allies reject the demand for NATO not to admit new members, emphasizing a key alliance principle is membership is open to any qualifying country and no outsiders have veto power. But Washington and NATO also said they are ready to discuss arms control, confidence-building measures, greater transparency and risk reduction if Russia takes a constructive stance.
U.S. Deputy Secretary of State Wendy Sherman said she briefed the North Atlantic Council on her talks in Geneva.
"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 tweeted.
The U.S. warned Russia will face unprecedented sanctions if it attacks Ukraine.
Amid the tensions, the Russian military said 3,000 troops were taking part in drills at firing ranges in the Voronezh, Belgorod, Bryansk and Smolensk regions near Ukraine.
In 2014, Russia annexed Ukraine's Crimean Peninsula after the ouster of its Moscow- friendly leader and threw its weight behind a separatist insurgency in the country's east, where more than seven years of fighting has killed more than 14,000 people.
A 2015 peace deal brokered by France and Germany has helped end large-scale battles, but frequent skirmishes have continued and efforts to negotiate a political settlement have failed.
Ukrainian President Volodymyr Zelenskyy met Tuesday in Kyiv with French and German officials on prospects for another meeting of the leaders of Russia, Ukraine, France and Germany, saying he wanted "substantive talks on ending the conflict."
Ukrainian Foreign Minister Dmytro Kuleba said he spoke with U.S. Secretary of State Antony Blinken on Tuesday, saying Kyiv and Washington "remain united in seeking de-escalation through diplomacy and strength."