In a virtual summit Tuesday, U.S. President Joe Biden laid out to his Russian counterpart, Vladimir Putin, the steps the U.S. will take should Moscow decide to invade Ukraine.
"If Russia further invades Ukraine, the United States and our European allies would respond with strong economic measures. We would provide additional defensive material to the Ukrainians above and beyond that which we are already providing. And we would fortify our NATO allies on the eastern flank with additional capabilities in response to such an escalation," Jake Sullivan, Biden's national security adviser, said in a briefing to reporters at the White House.
Sullivan said Biden offered Putin another option, "de-escalation and diplomacy."
According to the Kremlin, Putin emphasized the lack of progress by Ukraine in implementing the 2015 Minsk agreement, which was meant to stop the fighting in the Donbass region of eastern Ukraine, and he raised "serious concerns about the provocative actions of Kyiv in the Donbass."
The Russian leader accused NATO "of making dangerous attempts to conquer Ukrainian territory" and of building up its military capabilities near the Russian border, according to the Kremlin.
This is Biden's second virtual summit with an adversary. In his October meeting with Chinese President Xi Jinping, Biden discussed another territorial hot spot, Taiwan.
"If Russia is seen as getting away with invading Ukraine, and in somehow being seen as succeeding here, China will be watching this very closely and will see it as sort of as a dry run for potential operation against Taiwan," said Max Bergmann, a senior fellow at the Center for American Progress.
"The United States is going to take every action that we can take from the point of view of both deterrence and diplomacy, to make sure that the Taiwan scenario you just described never happens," Sullivan said in response to VOA's question on whether the U.S. is prepared to deal with the nightmare scenario of a Russian invasion of Ukraine and simultaneously China into Taiwan. "And to try to avert the invasion and deter the invasion into Ukraine, that is the object of our policy right now."
The White House said the two leaders also discussed strategic arms stability across the world, costly ransomware attacks emanating from Russia that have shut down computer networks at U.S. companies, and their joint efforts to curb Iran's nuclear weapons development.
Biden and Putin had a "productive" discussion on the Iran issue, Sullivan said in response to VOA's question.
"Russia and United States actually worked well together even in tense circumstances back in the 2014, 2015 period to produce the Joint Comprehensive Plan of Action," Sullivan said. "This is an area where Russia in the United States can continue to consult closely to ensure that Iran never acquires nuclear weapons."
After the call ended, Biden held a separate call with several U.S. allies to brief them on his conversation with Putin, including President Emmanuel Macron of France, Chancellor Angela Merkel of Germany, Prime Minister Mario Draghi of Italy and Prime Minister Boris Johnson of Britain. The White House said the allies will stay in close touch and work on "a coordinated and comprehensive approach."
Moscow has positioned 70,000 troops along Ukraine's eastern border, according to the U.S., with American officials suspecting an invasion is possible in early 2022. Russia annexed Ukraine's Crimean Peninsula in 2014, with then-U.S. President Barack Obama, and Biden as his vice president, condemning the takeover but not intervening militarily.
Ahead of the summit, White House officials said the U.S. would exact "a very real cost" against the Kremlin if it launches a new invasion.
Putin, in turn, wants the U.S. to guarantee that NATO, the post-World War II military alliance, will never expand to include Ukraine, a demand the Americans and their 29 allies will not accept. The White House made no mention of NATO in its readout of the talks.
On Monday, White House press secretary Jen Psaki said, "We've consulted significantly with our allies and believe we have a path forward that would impose significant and severe harm on the Russian economy" in the event of a Russian invasion of Ukraine.
"You can call that a threat," she said. "You can call that a fact. You can call that preparation. You can call it whatever you want to call it."
Administration officials say Moscow has launched a massive cyberspace disinformation campaign against Ukraine's government in Kyiv that echoes Russia's 2014 invasion and annexation of Crimea.
At the virtual summit, Biden spoke from the Situation Room at the White House and Putin from his retreat in Sochi.
Ahead of the talks, Kyiv contended that Russia is sending tanks and snipers to war-torn eastern Ukraine to "provoke return fire." Ukraine's Defense Ministry accused Russia of holding "training camps under the leadership of regular servicemen of the Russian armed forces."Moscow has not commented on the allegations.
WATCH: Biden talks to Putin about Ukraine
U.S. assures Ukraine of support
U.S. Secretary of State Antony Blinken spoke Monday with Ukrainian President Volodymyr Zelenskiy. A State Department spokesman said the top U.S. diplomat assured him of "the United States' unwavering support for Ukraine's sovereignty, independence, and territorial integrity in the face of Russian aggression."
U.S. intelligence has not determined whether Putin has made a final decision to invade.
Putin has been at a loss to curb NATO expansion. Numerous former Soviet-satellite states have been added to the 72-year-old alliance, including Poland, Hungary and the Czech Republic in 1999.
There is little prospect that Ukraine would be invited into NATO anytime soon, but the U.S. and its allies have not ruled it out. No outsider, such as Russia, has membership veto power.
Biden's talks with Putin came as opposition Republican lawmakers increasingly have criticized his performance on the world stage. They contend the Democratic president has done little to curb Iran's nuclear weapons development program, even though Tehran claims it is for peaceful purposes, or limit China's military strength in the Indo-Pacific region.
"Fellow authoritarians in Beijing and Tehran will be watching how the free world responds," Senate Minority Leader Mitch McConnell said of the Biden-Putin talks. "And President Biden has an opportunity to set the tone when he speaks with Putin."
Jamie Dettmer contributed to this report.