U.S. Vice President Kamala Harris is set to visit Ukrainian President Volodymr Zelenskiy in Munich on Saturday, in what is anticipated to be a powerful show of diplomatic solidarity for the European country, only a day after President Joe Biden claimed he is “convinced” Russia has decided to attack Ukraine.

According to a senior US administration official who spoke to reporters on the condition of anonymity, Harris will also deliver a highly anticipated address warning Russia that an invasion would likely result in an even larger NATO footprint on its doorstep and that it would face massive financial costs if it invaded Ukraine.

Her message, however, would make it clear that the US is open to dialogue “even at this late hour,” the person said, despite the fact that Biden and other administration officials have issued grave warnings that the window for diplomacy is closing.

On Friday, Harris met with NATO Secretary General Jens Stoltenberg and leaders from three Baltic states, saying Russia must demonstrate its willingness to engage in dialogue, while praising the 30-member NATO alliance and warning Moscow of dire repercussions if it invades Ukraine.

President Biden, who spoke later in the day, said Putin has decided to invade Ukraine, and that he continues to spread false information to try to build a pretext for a military strike that could happen in days.

Russia, which has said it has no plans to invade, wants to stop Kyiv from joining NATO and accuses the West of hysteria. On Friday, separatists backed by Moscow told civilians to leave breakaway regions on buses, a move the West fears is part of a pretext for an attack.

The Russian defense ministry said on Friday that Putin would oversee exercises by Russia’s nuclear forces involving the launch of ballistic and cruise missiles. The senior U.S. administration official called the decision “escalatory and unfortunate.”

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.”

Biden, when asked the same question, said “that’s a judgment for him to make.”

Zelenskiy has long said that, while he believes Russia is threatening to attack his country, the likelihood of an imminent invasion has been overstated by Western allies, responding to Moscow’s efforts to intimidate Ukraine and sow panic.