russian headquarters Izyum bomb
© Roland Oliphant and Sergio Olmos/The Telegraph
Ukraine strikes the Russian army headquarters in Izyum
Glimpse inside the city gives a sense of how complete and rapid the enemy's defeat was with evidence of Russia's panicked retreat everywhere

The Russian army headquarters in Izyum looks like it was hit by a hurricane.

Shattered walls, furniture in splinters, entire corridors scattered with rubble.

Underfoot, a June edition of Red Star, the Russian army newspaper, bearing the headline: "With precise focus on guaranteed results."

The irony could not be more bitter.

This command centre was destroyed by satellite-guided rockets from American-built Himars missile launchers - the precision weapons that underwrote a lightning Ukrainian offensive that liberated this city in just a few days late last week.

The first glimpse inside Izyum gives a sense of how complete and rapid the Russian defeat was.

But this is a city still in shock.

Not a single city block has escaped shell damage of some sort. About half of the windows in the town seem to have been blown out, but strangely almost none have been boarded up.

The streets are almost deserted. The only locals to venture out on Thursday afternoon were elderly civilians trying to find a truck distributing humanitarian aid.

"It was very hard," said Hirhory, a 63-year-old civil engineer, when asked about the occupation.

"First the Russians shelled civilian infrastructure: heating stations, bridges," he said of the first battle in spring.

"Then they hit us with cluster bombs, a lot of people were wounded. A lot of people were killed. Our home was blown in half. My apartment and my son's apartment are completely destroyed."

After the fear of the battle, came the privations of occupation. "It was hard, we didn't have electricity, gas, and water."

Then, very suddenly, it was over - and without a repeat of the agonising drawn out violence of the March battle.

"First day when our military hit them, they fled in a hurry. They left behind their ammunition and even their shoes," he said.

Izyum fell to Ukrainian forces on Saturday. On Wednesday, Volodymyr Zelensky, the Ukrainian president, and General Oleksandr Syrskyi, the senior officer credited with commanding the operation, arrived to inspect the damage themselves.

Ukrainian triumphalism is understandable.

The Russians captured Izyum, a normally sleepy city on the main highway between Kharkiv and Donetsk, after a month-long battle in March.

They quickly turned it into one of their most important logistics and command hubs, intending to use it for the springboard for their northern pincer of their grand summer offensive in the Donbas.

In the event, that effort stalled. But Izyum remained a major Russian stronghold, and for the Ukrainians, a grave threat. Slavyansk, the gateway to the Donetsk region, is just a 30-mile drive down the highway.

So the liberation of the city is not just a local victory: it has made Russia's declared political objective of "liberating" the Donbas impossible.

But like every Ukrainian advance since the liberation of Bucha in March, the euphoria is overshadowed by fear of what might be found.

Anton Herashenko, an advisor to the Ukrainian interior ministry, told the BBC on Thursday that about 1,000 bodies had been found in Izyum and that more civilians had died there than in Bucha.

The Telegraph did not see any evidence of that scale of death during a visit on Thursday. Hrigory denied knowledge of any war crimes.

"We didn't interact with them, and they didn't interact with us," he said of the Russians. "From what I know, there wasn't detentions, executions, torture."

"There were a lot of young men who would say 'we won't shoot any bullets,'" he added.

There is another unspoken, but troubling shadow to the advance.

Like civilians in all wars, those here seem wary of speaking.

When the flags change without warning, it is worth being careful what you say. Who knows which army will be in control next week.

Meanwhile, Mr Zelensky has promised to hunt down and jail "collaborators" who worked with the occupation.

Anton Chernyshov, a 31-year-old local, was arrested and jailed by Russia's FSB for stealing ammunition and throwing it into a swamp in what he calls his own "tiny partisan action".

He said attitudes in the town were mixed.

People gather on a square in Izyum after being freed from Russian forces Credit: JUAN BARRETO/AFP

About two thirds of the town fled when the battle began in March, but of those who stayed for the occupation about half were sympathetic to Russia, he said.

"They just believed the propaganda about the Russian world," he said. With the Internet cut off and only Russian newspapers and radio available, it was impossible to know if Ukrainian troops would ever return. "People still believed in Ukraine, but they were giving up, slowly," he said.

The people he called real "collaborators" fled with the Russians, he said. He said he saw a column of vehicles, containing anything up to a thousand people, leaving town once word got round about the retreat.

Weapons left behind

Evidence of the panicked Russian retreat is everywhere.

Not far from the concrete monument at the gates of the city where Ukrainian soldiers have been taking selfies lie the remains of a Russian strongpoint.

A few days ago, the trenches here evidently protected a bustling Russian firing position.

Beneath the trees they left dozens of rockets and cluster bombs for Uragan mulitple rocket launch systems. Some, but far from all, appear to have detonated.

Rockets and cluster bombs lie beneath the trees

Nearby, the carcass of a self-propelled howitzer, still emblazoned with the white Z of the invasion force, lies like a broken fossil.

A self-propelled howitzer, still emblazoned with the white Z of the invasion force, is abandoned

Russia's foreign ministry tried to lay out clear limits on the Western assistance that made this Ukrainian triumph possible, warning that deliveries of missiles with a greater range than those already provided would not be acceptable.

"If Washington decides to supply longer-range missiles to Kyiv, then it will be crossing a red line, and will become a direct party to the conflict," said Maria Zakharova, the ministry's spokesman.

She did not mention a particular weapon system but was likely referring to ATACMS rockets, which have a range of around 190 miles and can be fired by Himars systems.

The United States has admitted to supplying Ukraine's Himars with satellite-guided GMLRS rockets, which have a range of 50 miles.

However, a strike on a Russian airbase in Crimea, about 125 miles from the nearest frontline, has never been fully explained.

Local officials in the region around Mr Zelensky's hometown of Kryvyi Rih reported fresh Russian strikes on Thursday after attacks damaged a dam and saw dozens of homes flooded.

In the eastern Donetsk region, which has been partially controlled by Russian-backed separatists since 2014, fresh shelling killed two civilians and left another 13 wounded.