Ukrainian President Volodymyr Zelenskyy said the military is set to launch a counteroffensive against Russian troops but needs help from their European neighbors.

'If Europe waits," Zelenskyy warned European leaders Thursday, "the evil may have time to regroup and prepare for years of war."

In the video address, delivered from a train, Zelenskyy urged the leaders to expand and hasten their deliveries of weapons and ammunition to Ukraine to use in its campaign to beat back the Russian invasion.

The European leaders signed a $2 billion deal Thursday, endorsed earlier this week by EU foreign and defense ministers, calling for both sending ammunition from existing stocks and for EU countries to work together to place new orders for more rounds.

With Russia's attempt to capture Bakhmut stalled, the long-awaited counteroffensive will begin "very soon," Ukraine's top ground forces commander said Thursday.

Ukrainian Colonel-General Oleksandr Syrskyi said on the Telegram social media site that Russia's Wagner Group mercenaries, often convicts recruited out of prisons, 'are losing considerable strength and are running out of steam" in trying to take control of Bakhmut. After considering a pullout in the eastern city, Ukraine kept its troops in place, while also sending in reinforcements.

"Very soon, we will take advantage of this opportunity, as we did in the past near Kyiv, Kharkiv, Balakliya and Kupiansk,' he said, naming cities Ukraine has defended or captured from Russian control.

Syrskyi was one of the top commanders behind Ukraine's strategy last year in the first weeks of the war that repelled Russia's assault on Kyiv, the Ukrainian capital, and turned back Moscow's forces through the second half of 2022.

On Wednesday, Britain's Defense Ministry said Ukrainian forces had launched a local counterattack west of Bakhmut that was likely to relieve pressure on the main route used to supply Kyiv's forces inside the city.

The ministry said there was still a threat that Ukrainian forces in Bakhmut could be surrounded, but there was 'a realistic possibility the Russian assault on the town is losing the limited momentum it had obtained.'

The front lines of the war in eastern Ukraine have largely stalemated in recent months, with neither side able to capture significant new territory, even as they both sustain huge numbers of casualties.

Moscow has not commented on Ukrainian claims that it is losing momentum in Bakhmut, but Yevgeny Prigozhin, the Wagner Group mercenary boss, in recent days has pessimistically warned of a Ukrainian counterassault.

Earlier this week, Prigozhin published a letter to Russian Defense Minister Sergei Shoigu, warning that Ukraine is trying to cut off Wagner's forces from Russia's regular troops and demanding Shoigu act to prevent this. Prigozhin said there would be 'negative consequences' if he failed.

On Thursday, Zelenskyy continued his tour of frontline provinces, visiting the Kherson region in the south a day after meeting troops near Bakhmut. A video showed him meeting residents in Posad Pokrovske, a bombed-out village on the former Kherson frontline recaptured in Ukraine's last big advance last year.

'We will restore everything; we will rebuild everything. Just like with every city and village that suffered because of the occupiers,' he wrote.

Some material in this report came from The Associated Press, Agence France-Presse and Reuters.