Ukrainian President Volodymyr Zelensky, center, sings the Ukrainian national anthem during his visit to Izium, Kharkiv region, Ukraine, on Wednesday. Ukrainian Presidential Press Office via Associated Press

IZIUM, Ukraine — Hand on heart, Ukrainian President Volodymyr Zelensky watched his country’s flag rise Wednesday above the recaptured city of Izium, making a rare foray outside the capital that highlights Moscow’s embarrassing retreat from a Ukrainian counteroffensive.

Russian forces left the war-scarred city last week as Kyiv’s soldiers pressed a stunning advance that has reclaimed large swaths of territory in Ukraine’s northeastern Kharkiv region.

As Zelensky looked on and sang the national anthem, the Ukrainian flag was raised in front of the burned-out city hall. After almost six months under Russian occupation, Izium was left largely devastated, with apartment buildings blackened by fire and pockmarked by artillery strikes.

A gaping hole and piles of rubble stood where one building had collapsed.

“The view is very shocking, but it is not shocking for me,” Zelensky told journalists, “because we began to see the same pictures from Bucha, from the first de-occupied territories … the same destroyed buildings, killed people.”

Zelensky poses for a photo with soldiers after attending a national flag-raising ceremony in the freed Izium, Ukraine, on Wednesday. Zelensky greeted soldiers and thanked them for their efforts in retaking the area, as the Ukrainian flag was raised in front of the burned-out city hall building. Leo Correa/Associated Press

But in Kreminna, another city where Ukrainians raised their flag, Russians returned Wednesday and “tore down the (Ukrainian) flags and are demonstrably showing that they’re there,” Haidai said.

A separatist military leader confirmed the Ukrainian advance on the Luhansk region. Andrei Marochko, a local militia officer, said on Russian TV that the situation was “really difficult.”

“In some places, the contact line has come very close to the borders of the Luhansk People’s Republic,” Marochko said, referring to the independent state the separatists declared eight years ago.

The counteroffensive has left more weapons in Ukrainian hands.

Russian forces likely left behind dozens of tanks, armored personnel carriers and other heavy weaponry as they fled Ukraine’s advance in the east, a Ukrainian think tank said Wednesday.

The Center for Defense Strategies said one Russian unit fleeing the Izium area left behind more than three dozen T-80 tanks and about as many infantry fighting vehicles. Another unit left 47 tanks and 27 armored vehicles.

The center said Russian forces tried to destroy some of the abandoned vehicles through artillery strikes as they fell back. Typically, armed forces ruin equipment left behind so their opponent can’t use it.

However, the chaos of the Russian withdrawal apparently forced them to abandon untouched ammunition and weapons.

With the recent Ukrainian gains, a new front line has emerged along the Oskil River, which largely traces the eastern edge of the Kharkiv region, a Washington-based think tank, the Institute for the Study of War, said Wednesday.

“Russian troops are unlikely to be strong enough to prevent further Ukrainian advances along the entire Oskil River because they do not appear to be receiving reinforcements, and Ukrainian troops will likely be able to exploit this weakness to resume the counteroffensive across the Oskil if they choose,” the institute said.

In other areas, Russia continued its attacks, causing more casualties in a war that has dragged on for nearly seven months.

A Ukrainian soldier atop a military vehicle on the road in the freed territory of the Kharkiv region of Ukraine on Monday. Kostiantyn Liberov/Associated Press

Russian shelling of seven Ukrainian regions over the past 24 hours killed at least seven civilians and wounded 22, Ukraine’s presidential office reported Wednesday morning.

Two people were killed and three wounded after Russia attacked Mykolaiv with S-300 missiles overnight, said regional governor Vitaliy Kim. Settlements near the front line in Mykolaiv region remain under fire.

The Nikopol area, across a river from the shut down Zaporizhzhia Nuclear Power Plant, was shelled three times during the night, with no injuries were immediately reported, regional governor Valentyn Reznichenko said.

Fighting also raged in the eastern Donetsk region, where shelling killed five civilians and wounded 16. Together, Luhansk and Donetsk make up the Donbas, an industrial area that Moscow set out to capture following an unsuccessful attempt to invade Kyiv.

Russian troops are targeting critical infrastructure. Eight cruise missiles aimed at the water supply system hit Kryvyi Rih, a city 93 miles southeast of Dnipro. Deputy Head of President’s office Kyrylo Tymoshenko reported on his Telegram channel.

U.S. President Biden observed Wednesday that Ukrainian forces have made “significant progress” in recent days but said, “I think it’s going to be a long haul.”

While criticism of the invasion seems to be increasing in Russia, German Chancellor Olaf Scholz said after a phone call with Russian President Vladimir Putin, “Unfortunately, I cannot tell you that the realization has grown over there by now that this was a mistake to start this war.”

Western military and economic support have allowed Ukraine to keep fighting since Russia invaded on Feb. 24, and and the Ukrainian government received more assistance Wednesday.

An international group of creditors, including the U.S., finalized a deal to suspend Ukraine’s debt service through the end of 2023, helping the country ease liquidity pressures and increase social, health and economic spending.

Arhirova reported from Kyiva. Associated Press journalist Jon Gambrell in Kyiv contributed.