U.S. Vice President Kamala Harris speaks prior to President Joe Biden signing an executive order on federal construction project contracts and labor agreements during a visit to Ironworkers Local 5 in Upper Marlboro, Maryland, U.S., February 4, 2022.
U.S. Vice President Kamala Harris speaks prior to President Joe Biden signing an executive order on federal construction project contracts and labor agreements during a visit to Ironworkers Local 5 in Upper Marlboro, Maryland, U.S., February 4, 2022. Reuters / LEAH MILLIS

U.S. Vice President Kamala Harris met NATO Secretary General Jens Stoltenberg and leaders from three Baltic nations on Friday and said Russia must show it is open to diplomacy, while warning Moscow of severe consequences if it invades Ukraine.

The Russian defense ministry said earlier in the day that President Vladimir Putin would on Saturday oversee exercises by Russia's nuclear forces involving the launch of ballistic and cruise missiles. A senior U.S. administration official called the decision "escalatory and unfortunate."

Heralding NATO unity, Harris said "an attack on one is an attack on all," and the United States and its allies were ready to respond with sanctions if Putin decided to invade Ukraine.

"We understand and we have made clear that we remain open to diplomacy. The onus is on Russia at this point, to demonstrate that it is serious in that regard," Harris said.

The United States and European countries remain on high alert should Russia create a pretext for invasion. Her comments appeared aimed at sending Putin a message the crisis has bolstered the 30-country NATO alliance's resolve to push back against any Russian aggression.

At a news conference in Moscow, Putin said Russia needed to work on increasing its economic sovereignty. He said the West would always find a pretext to impose sanctions on Moscow.

Washington estimates that Russia has likely amassed between 169,000 and 190,000 military personnel in and near Ukraine, up from about 100,000 on Jan. 30, said Michael Carpenter, the permanent U.S. representative to the Organization for Security and Cooperation in Europe.

Biden on Thursday said the door to a diplomatic solution remains open but his sense was Russia would invade in the next several days. On Friday, Biden spoke to leaders of France, United Kingdom, Germany, Poland, Romania among others and pledged to pursue diplomacy to lower tensions while also ensuring readiness to impose swift, coordinated economic costs on Russia if it chose further conflict, the White House said.

Leaders from Latvia, Lithuania and Estonia said a show of unity, dialogue among allies, severe sanctions and reinforcement of NATO's eastern flank remained the only options to deter Russia.

"Today the ghost of war is lingering in Europe, unfortunately we have to admit it. We see possibility of military conflict in Ukraine," Lithuanian President Gitanas Naus?da said.

He asked for a "permanent presence" of U.S. troops in his country, stressing the only way to stop Russia was "deterrence."

During a three-day visit to the Munich Security Conference, Harris will also meet Ukrainian President Volodymyr Zelenskiy and German Chancellor Olaf Scholz and other world leaders on Saturday.

Asked if the United States is concerned about whether Zelenskiy should travel to Munich for meetings tomorrow, the senior administration official said, "No.

"That's really his call. It's really up to him to decide where he needs to be."