Like the first green shoot after a devastating bushfire, the blue-and-yellow Ukrainian flag was raised above the burned-out city hall in Izium on Tuesday, just days after the city was recaptured from Russian forces.
It’s one of dozens of settlements in Ukraine’s north-east Kharkiv region back under Ukrainian control, following lightning advances made by Kyiv’s soldiers last weekend.
Abandoned Russian tanks and armoured vehicles point to a chaotic retreat by the occupying force, which Moscow has tried to pass off as a “regroup”.
The surprise eastern counteroffensive, planned months in advance, has been hailed as a turning point in the war.
But it comes as a separate assault drags on in the south of the country, while Russia maintains its grip on the sprawling Donbass region.
Whether Ukraine can capitalise on the momentum that saw it claw back thousands of square kilometres relies on several key factors, not least the ongoing support of the West.
How Ukraine scored its biggest victory since the war began
It only took a few days for Ukraine to liberate as much territory as Russia had captured over several months, as the occupying force crumbled then withdrew from Izium on Saturday.
Ukraine appears to have borrowed a US military tactic favoured during the Iraq War called a “thunder run”.
The daring, high-speed manoeuvre involves a military convoy using heavy weapons and armoured vehicles to plunge into enemy territory and overrun the surprised defending forces.
Ukrainian President Volodymyr Zelenskyy has since claimed more than 6,000 square kilometres has been reclaimed in the east and the south since the beginning of September.
The situation was so dire in some towns and villages, residents later told reporters, that Russian troops were seen fleeing on stolen bicycles, attempting to disguise themselves in civilian clothes.
“The Russian army these days is demonstrating its best ability — to show its back,” Mr Zelenskyy said in a video address.
The eastern city of Izium is a logistical hub and the gateway to the Donbass region, which includes the two Russian-controlled separatist states Donetsk and Lugansk.
Winning the city back, combined with Ukraine’s other sweeping gains, is perhaps the biggest upset in the war since Russia’s dramatic retreat from the capital Kyiv in late March.
But less than a fortnight ago, the battle for the southern port city of Kherson seemed to be Ukraine’s main priority.
So, did something change? Or was a southern fake-out always on the cards?
The tightly held plan that caught Putin off guard
It all began with a war game.
With the deadline of winter looming, the Ukrainian president needed a consequential win to boost his people’s morale and shore up future support from the West.
“Slowly Ukraine was starting to lose face and the Western countries were starting to lose faith in the Ukrainian Armed Forces,” said Marina Miron, a research fellow in the Defence Studies Department at King’s College in London.
“So, first of all, they saw themselves under pressure to deliver something, to deliver some sort of victory.
“Because, before that, all the victories were essentially in the information domain, but you have to show something on the battlefield.”
The Ukrainian military devised a plan to reclaim Kherson and Mariupol, both home to prized ports, hoping to turn the tide six months into the war.
During the summer, US and Ukrainian officials teased out the possibility of a broad offensive in the south targeting the strategic cities, which grant access to the Black Sea.
But the exercise, first reported by CNN, suggested such an ambitious blitz was doomed to fail.
The Ukrainians were adamant, though: they needed to move quickly to stop Moscow further exploiting its control of gas supplies to Europe when the chill sets in.
The continent has already seen a dramatic spike in energy prices, with Russia’s deputy prime minister now promising to cut gas exports by a third.
Drawing on US intelligence, the Ukrainians planned two smaller offensives.
They hoped to turn their dominance in the information sphere — plus an influx of new weaponry — into a decisive win on the ground.
Did the US tip the scales?
For the past several months, the conflict has ground on in the east and the south with neither side seemingly able to break the stalemate.
But, behind the scenes, Ukraine was quietly amassing billions of dollars’ worth of foreign military aid — and learning how to use it.
Since the war began on February 24, the United States alone has injected some $US14.5 billion ($21.7 billion) into the war, including providing HIMARS, a type of powerful long-range rocket launcher.
The munitions for the GPS-guided systems can strike targets with precision from more than 60 kilometres away.
By some accounts, the five-tonne HIMARS trucks, the first of which arrived in June, are having an outsized impact on the battlefield because they allow the Ukrainians to hit targets deep behind enemy lines.
But Dr Miron argued US intelligence probably played a weightier role.
“I think the importance of HIMARS was basically, in a tactical sense, it created some parity in terms of artillery,” she said.
“However, I don’t think it was the catalyst of change in this war.”
It now seems likely the two-pronged offensive — capturing the east while eyes were on the south — was always the plan.
“The Ukrainians are conducting operations that are forcing the Russians to make decisions on the battlefield about where they’re going to apply their resources, and how,” a senior US military official said during a recent Pentagon briefing.
“So, what we’ve seen is the Ukrainians applying the capabilities that they have, [including] those that have been provided by the US and our allies … in order to again change the dynamics on the battlefield.”
But the strategic masterstroke, and the thousands of soldiers needed to pull it off, came from the Ukrainians alone, the official was careful to note.
Taras Berezovets, a former Ukrainian national security adviser turned special forces press officer, went so far as to label the tactic a “big special disinformation operation”.
“[Russia] thought it would be in the south and moved their equipment,” he told the Guardian.
“Then, instead of the south, the offensive happened where they least expected, and this caused them to panic and flee.”
Why Ukraine’s timing was everything
In Russia, President Vladimir Putin has carefully stage-managed the domestic coverage of the invasion of Ukraine.
He still refuses to call it a war, instead euphemistically describing it as a “special military operation”, meant to “de-Nazify” Ukraine and liberate its people.
On state television, he has consistently been backed by a cheer squad of presenters parroting Kremlin talking points.
But even some of Mr Putin’s most ardent supporters appear shaken by Ukraine’s change of fortunes.
The frustration is also starting to seep through online.
“We need to be honest, the Ukrainian command has outplayed us here,” said Yuri Podolya, a pro-Kremlin military blogger with 2.2 million followers on Telegram.
Mr Podolya called the recent losses “large” and said the Russian Ministry of Defence had failed to rectify “problems identified by the first months of the war”.
On the world stage, Russia is also becoming increasingly isolated, even from its most powerful allies.
In separate meetings with Mr Putin this week, Indian Prime Minister Narendra Modi appeared to tacitly rebuke the invasion of Ukraine, while China’s leader Xi Jinping made no mention of it at all.
“I know that today’s era is not an era of war,” Mr Modi said.
Mr Putin has held power in Russia since 1999, both as president and prime minister.
His potential electoral opposition has been sidelined — or jailed — but he is acutely sensitive to public sentiment.
He’s also spent roughly two decades building up Russia’s modern military, once ranked among the world’s best, which now appears to be in tatters.
In a statement, the Ministry of Defence sought to frame Russia’s hasty retreat as a pre-planned decision to regroup and redeploy.
But it has already lashed out with missile strikes on critical infrastructure, plunging parts of the country into darkness and flooding Mr Zelenskyy’s hometown.
“Strength is the only source of Putin’s legitimacy,” Abbas Gallyamov, a former speechwriter for Mr Putin, told The New York Times.
“And in a situation in which it turns out that he has no strength, his legitimacy will start dropping toward zero.”
Is this the beginning of the end of the war?
The Ukrainians are hoping the West will help them solidify their gains in what remains contested territory, while trying to rebuild cities devastated by months of Russian occupation.
After surveying the destruction left behind in Izium, including mass graves, Mr Zelenskyy has also called on foreign governments to investigate alleged human rights abuses.
“Earlier, when we looked up, we always looked for the blue sky,” he wrote in a statement.
“Today, when we look up, we are looking for only one thing — the flag of Ukraine.”
His foreign minister, Dmytro Kuleba, also condemned the recent missile strikes on water systems as “a war crime” and an “act of terror”.
It remains unclear how far Russia will be willing to go to halt Ukraine’s momentum.
But some fear cyber, chemical and even nuclear attacks may be on the cards.
So far, the European Union’s top official, Ursula von der Leyen, has been a sympathetic ear.
“It’s absolutely vital and necessary to support Ukraine with the military equipment they need to defend themselves,” she said.
But the US has rebuffed a request to provide more HIMARS munitions.
“I’m not sure that Ukraine will get the weapons it’s requesting because … the West [is] not interested in having Ukraine so powerful that it can potentially launch attacks deep inside Russia, because then everything would spin out of control,” Dr Miron said.