As tens of thousands of invading Russian troops and tanks thundered across his nation's border in February 2022, Ukrainian President Volodymyr Zelenskyy received an offer from the United States to evacuate him and his family out of the country.

But in the biggest moment of his yet budding political life, with a world superpower bearing down with brutal force, Zelenskyy rejected the offer to escape, replying, "The fight is here; I need ammunition, not a ride."

A year later, he and his country are still standing strong, forcefully pushing back against Russian President Vladimir Putin's aggressive campaign to pummel Ukraine into submission.

Zelenskyy set the defiant tone for his country just hours after the war started. He shed his suits and ties for military fatigues and combat boots, and boldly posted a selfie video message to the frightened citizens of his nation. Standing on a street outside his office in the capital city of Kyiv, members of his cabinet and military advisors at his side, the then-44-year-old Zelenskyy stared into the camera and announced he and his leadership team were staying put.

"We are all here defending our independence and we are defending our country and we will keep doing that," he said.

It was a dramatic rallying cry that echoed around the world and began the transformation of Zelenskyy into a wartime hero with some admirers even comparing him to Great Britain's Winston Churchill standing up to Nazi Germany during World War II.

-ABC News' Bill Hutchinson

Poland announced Friday that it has provided Ukraine with its first Leopard tanks to aid the fight against Russia.

"The Leopard tanks will definitely stand up well in your formation on the battlefield. They will work great," Polish Prime Minister Mateusz Morawiecki told Ukrainian President Volodymyr Zelenskyy during a visit to Kyiv to mark the one-year anniversary of Russia's full-scale invasion.

Poland delivered four Leopard 2A4s -- a model of the latest version of the German main battle tank -- to Ukraine, with more expected to be on the way, according to Morawiecki.

"We will also soon hand over more and we urge our partners from the European Union and NATO to do the same," Morawiecki said.

-ABC News' Joe Simonetti

Ukrainian Foreign Minister Dmytro Kuleba said Friday that his country will do "whatever it takes" to defeat the Russian invaders.

"This war has no timeline. It has only [one] result in the end and that's victory, because we stand for the right cause," Kuleba told ABC News’ George Stephanopoulos during an interview on "Good Morning America."

"We defend ourselves. We are liberating our territory with generous support of many countries of the world, with the United States being at the top of it," he added. "I want to convey the words of gratitude from the people of Ukraine to the people of America for standing by us in this very just struggle for freedom and peace."

Kuleba noted that "ammunition, tanks, long-range missiles, planes" are the "most-wanted weapons" on Ukraine's list.

"I have no doubt that we will prevail," he said. "But, you know, for David to be able to defeat Goliath, David needs a sling. And all of these weapons, it's all about this sling that will help us to win."

Kuleba said Ukrainians are fighting for "territorial integrity."

"If you are attacked, you have to fight. You have to take up the fight and defend your country," he added. "And this is the feeling that drives us through all of this endless suffering."

When asked whether there's any kind of peace proposal that could be accepted by both sides, Kuleba said: "As of now, we are irreconcilable."

"Because while we defend our territory, [Russian President Vladimir Putin] wants to grab our territory. While we want accountability for numerous atrocities committed by the Russian army in Ukraine, Putin wants to escape responsibility," he explained. "This aggression of Russia will go down in textbooks as the most apparent case of aggression in modern history. So the truth is on our side and this is why we feel so empowered to fight and to win."

4:46

Ukrainian foreign minister Dmytro Kuleba talks 1-year anniversary of war with Russia

Speaking to ABC News' George Stephanopoulos on "Good Morning America," U.S. Secretary of State Antony Blinken discussed where things stand in the Russia-Ukraine war on Friday, one year after it began.

"Ukraine is still standing, it remains free, it remains independent," Blinken said. "Putin's first objective was to erase Ukraine from the map, to erase its identity, to absorb it into Russia. That has failed and will never succeed."

"Now, there's a fierce battle going on for the territory that Russia has seized," he added. "Ukraine's gotten about 50% of what Russia's taken since last February and now, there's a fight for the rest."

When asked how long Ukraine can hold on, with its economy devastated and Russian President Vladimir Putin seemingly preparing for a long war, Blinken said he thinks "the Ukrainians are the ones who are going to fight to the finish."

"There's one big difference: The Ukrainians are fighting for their country, for their land, for their future; the Russians are not," he noted. "And at the end of the day, assuming the support continues from so many countries around the world -- material support, military, economic, humanitarian -- Ukraine will succeed."

Blinken said it's "hard to predict" when the war will end.

"No one wants peace more than the Ukrainians, but it has to be a just and durable peace," he added. "Just in terms of reflecting the basic principles that are at the heart of the U.N. Charter, which is territorial integrity of countries, their sovereignty. And durable in the sense that wherever it lands, we don't want it to land in place where Russia can simply repeat the exercise a year or two or five years later."

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Sec. Blinken talks 1-year anniversary of Russian invasion of Ukraine

The U.S. estimates that Russia has suffered over 100,000 casualties, including over 20,000 killed in action, since it stepped up its winter offensive in December, a White House National Security Council told ABC News.

Half of the 20,000 killed in action were members of the Russian-backed private military Wagner Group, according to White House spokesman John Kirby. The majority of Wagner fighters killed were allegedly ex-convicts, according to Kirby.

Kirby said that the data came from "some downgraded intelligence" that the U.S. has been able to collect. He was unable to provide data on deaths of Ukrainian fighters.

Kirby had earlier told reporters that the Russian casualties took place from battles in Bakhmut since December, however, the National Security Council member said the data encompasses all winter battles.

Many, but not all, of these Russians were injured or killed in the Bakhmut fighting, according to the official.

Kirby emphasized that the U.S. thinks Bakhmut holds "very little strategic value for Russia" and if captured by Russia, it "would absolutely not alter the course of the war in Russia’s favor."

-ABC News' Ben Gittleson