Russia-Ukraine updates: US to ban Russian carriers from its airspace

The U.S. embassy in Moscow is warning Americans to avoid crowds and to stay alert in places frequented by tourists and Westerners. 

"According to media sources, there have been threats of attacks against shopping centers, railway and metro stations, and other public gathering places in major urban areas, including Moscow and St. Petersburg as well as in areas of heightened tension along the Russian border with Ukraine," the security alert, released Sunday, states.

It is unclear whether the alert is directly related to the heightened tensions over Russia's potential invasion of Ukraine or what "media sources" the embassy is referring to. 

"Have evacuation plans that do not rely on U.S. government assistance," the embassy advised.

-ABC News’ Conor Finnegan

Lower-level Russian tactical commanders have been given orders consistent with orders to invade Ukraine, U.S. officials tell ABC News. 

The news is consistent with statements previously made by President Joe Biden and Secretary of Defense Lloyd Austin, who have said they believe U.S. intelligence indicates Putin has made a decision to invade Ukraine.

-ABC News’ Luis Martinez

French President Emmanuel Macron and Russian President Vladimir Putin spoke Sunday by phone in an apparent last-ditch effort to discourage the Russian president from invading Ukraine.

Macron claimed that he and Putin agreed to "resume the work" of the Normandy Format peace talks, the long-running negotiations mediated by France and Germany and aimed at ending the war in eastern Ukraine between Russian-controlled separatists and Ukraine's government.

Macron's office says the agreement was made on the basis of "the exchanges and proposals made by Ukraine in recent days."

The Kremlin's readout of the call, though, did not say the two had agreed to anything concrete on the Normandy Format and noted Putin has accused Ukraine of only "initiating" negotiations. Putin did agree to intensify the search for a diplomatic solution, given "the severity" of the situation, the Kremlin said in a statement.

During the call, Putin blamed the escalation around eastern Ukraine on the Ukrainian military and expressed "serious concern" about the "sharp deterioration" around the frontline there, according to the Kremlin. 

Following the call, Macron spoke by phone with Ukraine's President Volodymyr Zelenskyy for 30 minutes, according to the French president's office.

Afterward, Zelenskyy tweeted that Ukraine wants an immediate "regime of silence" to be observed in eastern Ukraine and called for the Trilateral Contact Group that helps mediate ceasefire violations to be immediately convened amid the intensified shelling in the region as Russia continues to build an apparent pretext for an attack.

Vice President Kamala Harris is confident the threat of sanctions from U.S. and European partners will "absolutely" deter Russia from invading Ukraine, even if Putin has made up his mind, she told reporters before departing Munich to return to the U.S. on Sunday. 

Harris reaffirmed the statement President Joe Biden made on Friday — that Putin has already made his decision to invade. 

"We believe Putin has made his decision," she said. "Period."

When asked by ABC News foreign correspondent Molly Nagle about whether the U.S. has enough leverage for those sanctions to make a difference, Harris reiterated that sanctions are the best tactic, especially since allies "sincerely hope that there is a diplomatic path out of this moment."

"Remember, also, that the sanctions are a product not only of our perspective as [the] United States, but a shared perspective among our allies," she said. "And the allied relationship is such that we have agreed that the deterrence effect of these sanctions is still a meaningful one."

Harris also said that Ukrainian President Volodymyr Zelenskyy is in a difficult position on joining NATO, since it faces imminent threat from Russia, and emphasized the “significance” of a potential war in Europe.

"It's been over 70 years, and through those 70 years, as I mentioned yesterday, there has been peace and security," she said. "We are talking about the real possibility of war in Europe."

-ABC News’ Justin Gomez