President Joe Biden made an unannounced, symbolic visit to the capital city of Kyiv and pledged that the US would support Ukraine in its conflict with Russia for "as long as it takes.".
We are completely confident that you will keep winning, he added.
Days before the anniversary of Russia's invasion, Vice President Biden makes his first trip to Ukraine. .
Putin had been "dead wrong," according to him, to believe that Russia could outlast Ukraine and its allies in the West.
Volodymyr Zelensky, the president of Ukraine, and Mr. Biden recently met. While there, the two went to a memorial for soldiers who have died in the nine years since Russia annexed Crimea and its proxies took over some of the eastern Donbas region.
His presence is meant to demonstrate once more America's "unwavering commitment to Ukraine's democracy, sovereignty, and territorial integrity," according to a statement from the White House.
The New York Times reported that President Biden arrived in Kyiv after a 10-hour train ride from Poland.
More military aid, such as ammunition and air surveillance radars, is anticipated from Mr. Biden for Ukraine.
Later this week, there will also be an announcement of a fresh round of sanctions against people and organizations "that are trying to evade or backfill Russia's war machine.".
The results of this visit will undoubtedly be felt and seen when liberating our territories on the battlefield, according to Mr. Zelensky. ".
Additionally, he stated that the two leaders had discussed the prospect of sending additional weapons that had not yet been provided.
The US and other allies have so far refrained from approving Mr. Zelensky's repeated requests for F-16 fighter jets.
A few hours prior to President Biden's departure, the US informed Russia about the trip for "deconfliction purposes," according to national security adviser Jake Sullivan, who was in the president's entourage.
On Moscow's reaction to the news, he would not comment.
The trip had been planned for "months," according to White House officials, and the decision to go ahead with it was made on Friday.
Air raid sirens wailed while President Biden and Mr. Zelensky were in St. Michael's Cathedral in central Kyiv, adding drama to the most high-profile visit to Ukraine since the war started.
Other world leaders have traveled to Ukraine in the past year, but the US president's appearance in the nation's capital during a conflict in which American troops are not engaged is a sign of unity at a time when Russia claims Western support for Ukraine is dwindling.
In Kiev, Ukrainians welcomed the visit.
According to Roksoliana Gera, who spoke to the BBC, "I'm so grateful for his support - it means so much to us.".
"I admire his bravery for taking on this challenge and for coming to show the American people's support. ".
Oleksandra Soloviova referred to the visit as "a significant sign for the entire world.".
It demonstrates to Russia, she said, "that the US supports us and will continue to support us, with sanctions and military hardware.".
One of Ukraine's largest allies, the US has so far announced $24.9 billion (£20 point6 billion) in military aid, according to the US State Department.
Mr. Biden stated in January that 31 battle tanks and longer-range missiles would be sent by the US.
The amount of aid that Kyiv should receive in the future is a topic of growing political contention in the US.
A three-day trip to Poland follows President Biden's visit to Kyiv.
He will have meetings with Andrzej Duda, the president of the nation, and other Eastern European Nato allies there.