Russia's invasion of Ukraine has already engaged around 330,000 Russian personnel, Brigadier General Oleksiy Hromo of the General Staff of the Ukrainian Armed Forces told local media on Thursday.

“[Russian] groups at various axes are close to 150,000 strong. If we add their air and sea components, there are about 220,000 military personnel,” Hromo said. Russia also deployed “units of the national army combat reserve, the federal service of guard forces, and mobilization units,” the Brigadier General added.

Hromo's sobering account came on the back of claims made by a top Ukrainian official earlier on Wednesday that revealed mounting Ukrainian casualties. Up to 1,000 Ukrainian soldiers are being killed or wounded each day in the Donbas region of eastern Ukraine, with 200 to 500 killed on average and many more wounded, said David Arakhamia, who heads the presidential faction in the Ukrainian parliament.

In early June, Ukrainian President Volodymyr Zelenskyy said daily fatalities among Ukrainian ranks at the Donbas front were between 60 to 100 troops.

Arakhamia, one of Zelenskyy's closest advisers who oversees Ukraine's stalled negotiations with Russia, has been leading a Ukrainian delegation in Washington this week in a bid to lobby the Biden administration and Congress.

Arakhamia's team want to see the pace of weapons shipments increased and is pushing for a designation of Russia as a state sponsor of terrorism.

-ABC News' Edward Szekeres, Yuriy Zaliznyak, Yulia Drozd and Max Uzol

The United Kingdom announced a new wave of sanctions on Thursday targeting Russians involved in the barbaric treatment of children in Ukraine.

Maria Lvova-Belova, Russia's Children Rights Commissioner, tops the new list of sanctioned individuals for her alleged involvement in the forced transfer and adoption of Ukrainian children. She has been accused of enabling 2,000 vulnerable children being violently taken from the Luhansk and Donetsk regions and orchestrating a new policy to facilitate their forced adoptions in Russia.

“Today we are targeting the enablers and perpetrators of [Russian President Vladimir] Putin’s war who have brought untold suffering to Ukraine, including the forced transfer and adoption of children,” U.K. Foreign Secretary Liz Truss said in a press release.

More than 900 children were injured in Ukraine as a result of the full-scale armed aggression by the Russian Federation, according to the Ukrainian Prosecutor General’s latest report. Over 320 children were killed and more than 580 were injured.

These figures are far from being final, with more information slowly trickling in from places of active hostilities, as well as the temporarily occupied and liberated territories.

The UK's sanction list also includes Patriarch Kirill, the head of the Russian Orthodox Church, for his support and endorsement of Putin’s war.

Several members of Putin's political elite, along with four Military Colonels from a unit known to have killed, raped and tortured civilians in the Ukrainian town of Bucha, appear on the list too.

“Putin’s allies continue to choose to turn a blind eye to alleged war crimes and support his bloody offensive,” the U.K. government said. With Putin’s aggression reaching beyond Ukraine as Russian exports fuel conflict across the globe, the official press release read, the new sanctions also hit Myanmar’s military Junta.

The Junta relies heavily on Russian air assets and limiting it will cut Putin off from profiting from sales that fund his war machine, the U.K. said.

-ABC News' Edward Szekeres, Yuriy Zaliznyak, Yulia Drozd and Max Uzol

The State Department has still not confirmed reports that two former U.S. service members who volunteered to help Ukrainian forces have gone missing, spokesperson Ned Price said Thursday.

The Americans, Andy Tai Ngoc Huynh and Alexander Drueke, are both from Alabama.

"We are limited in terms of what we know at the moment," Price said. "We're closely monitoring the situation we are in contact with Ukrainian authorities, as well as with the International Committee of the Red Cross, and the families of the two reported missing U.S. citizens."

The department has not "seen anything from the Russians indicating that two such individuals are in their custody," Price said.

"If the Russians were to claim that they had such individuals, I assume we would pursue that. If we had reason to believe -- credible reasons to believe -- that these individuals were in Russian custody, we would pursue that as appropriate," Price continued.

Price was asked whether the department was tracking any other cases of Americans purportedly captured on the battlefield, and he said the department was aware of reports about "one additional American whose whereabouts are unknown.”

"Similarly, our understanding was that this individual had traveled to Ukraine to take up arms," Price said. He said the person was identified as missing "in recent weeks" and that the State Department was also in contact with their family.

Alabama Rep. Terri Sewell said that Drueke’s mother reached out to her office after losing contact with him. Sewell is helping the family locate him. Alabama Rep. Robert Aderholt said his office is helping in the search for Huynh after his family reached out to the congressman's office this week.

-ABC News' Shannon Crawford

In the first visit of EU leaders to the Ukrainian capital since Russia’s invasion, German Chancellor Olaf Scholz, French President Emmanuel Macron, Italian Prime Minister Mario Draghi and Romanian President Klaus Iohannis made clear their message of support and solidarity.

Scholz said, "My colleagues and I came here to Kyiv today with a clear message: Ukraine belongs to the European family."

Macron added, "All four of us support [Ukraine's] immediate EU candidacy."

The leaders discussed the possibility of further sanctions against Russia as well as how to rebuild Ukraine after the war.

Earlier in the day, the EU leaders toured Irpin, a town northeast of Kyiv, which was hit by heavy Russian artillery early in the war.

-ABC News' Britt Clennett and Ibtissem Guenfoud

As news spread of a successful evacuation operation from the besieged Azovstal steel plant in Mariupol, the deputy commander of the Azov battalion, Svyatoslav Palamar, said there was little reason to celebrate.

“Not enough is being done to try and evacuate wounded soldiers,” Palamar said, speaking at a press conference at the plant, which is surrounded by Russian forces.

Ukraine's Deputy Prime Minister Iryna Vereshchuk said Saturday the first stage of the rescue operation had concluded and all civilians had been evacuated from the steel plant. Another 173 people were rescued Sunday from Azovstal and surrounding Mariupol, according to the local city council.

But Palamar said some civilians might still be trapped under the rubble of ruined shelters and that many bodies of deceased troops and civilians remain uncollected on the plant's territory.

More than 25,000 people, most of them civilians, have been killed in Mariupol, according to Azov commanders. Half of all Russian bombardment and shelling in Ukraine was aimed at Mariupol, the battalion commanders said, adding that the city was shelled 150 times a day on average.

Russia has lost about 2,500 troops, with a further 500 wounded and over 60 destroyed tanks, in the city, Azov officials claimed. Yet the unblocking of Mariupol by military means remains difficult due to the lack of heavy weapons, Ukrainian President Volodymyr Zelenskyy said during a joint press conference with Canadian Prime Minister Justin Trudeau in Kyiv on Sunday.

Russia continued over the weekend to shell Ukrainian cities. Zelenskyy said Russians have “celebrated” the Day of Remembrance and Reconciliation on May 8 by launching nine missile strikes against Odessa. Zelenskyy spoke at a press briefing in Kyiv held after his talks with visiting Croatian Prime Minister Andrej Plenkovic. The Ukrainian President also met the head of the German parliament, Baerbel Bas, on Sunday. The two leaders spoke about how “German leadership in the European Union” can help Ukraine, Zelenskyy said in his nightly address on Sunday.

Ukrainian Foreign Minister Dmytro Kuleba tweeted Sunday that Berlin made a mistake by prohibiting Ukrainian symbols and flags at rallies during events on May 8-9.

“It's deeply false to treat them equally with Russian symbols,” Kuleba wrote, adding that “taking the Ukrainian flag away from peaceful protestors is an attack on everyone who now defends Europe and Germany from Russian aggression with a flag in their hands.”

On Monday, as Ukraine celebrated the Day of Victory over Nazism in World War II, Zelenskyy said that the ongoing conflict was “not a war of two armies. This is a war of two worldviews.”

Russian missiles are trying to destroy Ukrainian philosophy, Zelenskyy said, because it "scares them.”

“We are free people who have their own path,” the president said. “Today we are waging war on this path and we will not give anyone a single piece of our land.”

-ABC News' Edward Szekeres, Fidel Pavlenko, Irene Hnatiuk, Max Uzol and Uliana Lototska