The tide appears to have turned.
In a development that stunned the watching world as much as the Kremlin, Ukrainian troops have set Russian President Vladimir Putin back on his heels after more than six months of grinding conflict — raising hopes that Kyiv could push on and drive Moscow's invaders out of even more territory.
Ukrainian forces have routed Russian soldiers from the northeastern region of Kharkiv, forcing Putin's men to retreat after a surprise counteroffensive left the Kremlin's cheerleaders scrambling to adjust and its military racing to gather its defenses in the east and south.
President Volodymyr Zelenskyy said Monday his country's military had retaken around 6,000 square kilometers (2,400 square miles) of territory this month, roughly the size of Delaware.
NBC News has not verified the claims.
Ukrainian President Volodymyr Zelenskyy captured the increasingly optimistic mood in his country in stirring remarks and triumphalist comments on social media.
“Do you still think you can intimidate, break us, force us to make concessions?” Zelenskyy wrote Sunday on his verified Facebook page. “Did you really not understand anything? Didn’t understand who we are? What we are for? What we are talking about?”
Seeking to press their advantage, Ukrainian forces on Monday kept pushing deeper into territory previously controlled by Russian troops. Military and security analysts say the operation has demonstrated to the world — and in particular Kyiv’s Western allies — that Putin’s forces are drained and depleted by months of stern Ukrainian resistance.
“The significance of the latest developments lies not only in the extraordinary advance of Ukrainian forces but also in the convincing demonstration that it can seize the initiative and liberate territory from Russia at a high rate,” Keir Giles, a Russia expert and a senior consulting fellow at Chatham House, a London think tank, told NBC News. He said the recent events were a “turning point” in the war.
The counteroffensive represents "an inflection point, a high water mark, a clear moment" in the war, said John Spencer, a retired U.S. Army major and the chair of Urban Warfare Studies at the Madison Policy Forum, a research organization in New York.
Russia’s recent setbacks are even beginning to color the typically jingoistic tone of state television, with one commentator appearing to blame Putin’s advisers for steering him to war in the first place.
“The people who convinced President Putin that the special operation would be short and effective, that we would not hit the civilian population … these people simply set up all of us,” said Boris Nadezhdin, a former Russian legislator and political analyst who is known for taking a more balanced public view.
The Kremlin insisted Monday that Putin will not back down.
“The special military operation continues and will continue until all the goals that were originally set are achieved,” Putin spokesman Dmitry Peskov said in a conference call with reporters.
"If he was smart, he would try to end the war now and negotiate," said Phillips O'Brien, a professor of strategic studies at the University of St. Andrews in Scotland. "But it doesn't look like he's going to do that, at least not right away."
In Kyiv, residents were buzzing with enthusiasm.
"I spent the last few days glued to the screen, reading the news as religiously as I did ... in March," said Olexandr Shpygunov, 34, an information technology specialist. "I just had to see every new photo, every liberated village, every updated map."
"I feel like everyone I know has been doing pretty much the same," Shpygunov added.
He said he cannot help but think of the sacrifices the men and women on the front lines have made, but "seeing our soldiers' faces when they raise another Ukrainian flag, seeing the people who lived for months in occupation now greeting them with smiles and flowers and tears of joy — it has to be worth it."
Continued success will likely require ongoing support from the United States and the West, which is why Kyiv's latest battlefield gains were "important not only for the military situation in Ukraine but also for the broader political backing of Western supporters," Giles said.
But that doesn't mean Ukraine is now on a certain path to victory.
"Ukraine has turned the tide in its favor, but the current counter-offensive will not end the war," the Institute for the Study of War, a U.S.-based military think tank, cautioned in an update Sunday.
Kyiv remains vulnerable on several fronts, too.
Giles said that many of its soldiers are almost certainly "overstretched" and exhausted after more than 200 days of battles with Putin's invaders.
"The problem of Ukrainian fatigue will be temporarily lifted" as the country rallies behind Zelenskyy's defiance and the military's rapid advancements, "but it has not gone away," Giles said.
Cities in the region from which Russian troops pulled out over the weekend have faced increased bombardment, temporarily knocking out power and water supplies.
Ukraine also faces the practical hardships of the upcoming winter months, when the battlefield ground could freeze and Putin's energy war might exact an even steeper price on much of Europe, straining working families and global political will.
"Ukraine will have challenges in winning this war but also showing Europeans that the economic pain will be worth it," Giles said.
O'Brien added that Ukraine should be careful not to make any assumptions about Russia's resolve or the durability of its improved position.
"It's key that they don't let victory go to their head," he said.