The Americans, Andy Tai Ngoc Huynh and Alexander Drueke, are both from Alabama.
Russian President Vladimir Putin's "special military operation" into neighboring Ukraine began on Feb. 24, with Russian forces invading from Belarus, to the north, and Russia, to the east. Ukrainian troops have offered "stiff resistance," according to U.S. officials.
The Russian military has since launched a full-scale ground offensive in eastern Ukraine's disputed Donbas region, capturing the strategic port city of Mariupol and securing a coastal corridor to the Moscow-annexed Crimean Peninsula.
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A look at the two leaders at the center of the war in Ukraine and how they both rose to power, the difference in their leadership and what led to this moment in history.
Mass shelling of the Sumy region continued from Russian territory Wednesday evening, said Dmytro Zhyvytskyy, the governor of Sumy, on Telegram.
The shelling was along the entire border between the Sumy region and Russia, according to Zhyvytskyy.
Zhyvytskyy said Ukraine responded to the shelling appropriately and no casualties were reported.
-ABC News' Joe Simonetti
Mykhaylo Podolyak, an adviser to Ukrainian President Volodymyr Zelenskyy, told Russia not to offer Ukraine a cease-fire, because it would be impossible without Russian troops' withdrawal.
"Ukraine is not interested in new 'Minsk' and the war renewal in a few years," Podolyak said in a tweet, referring to the capital of Belarus and that country's allegiance to Russia. "Until [Russia] is ready to fully liberate occupied territories, our negotiating team is weapons, sanctions and money."
-ABC News' Joe Simonetti
The International Committee of the Red Cross said Thursday that it has registered hundreds of Ukrainian prisoners of war from a besieged steel plant in war-ravaged Mariupol this week, after the Ukrainian city fell into Russian hands.
A team from the ICRC began on Tuesday to register combatants leaving the Azovstal Iron and Steel Works plant, including the wounded, at the request of the parties to the conflict. The operation continued Wednesday and was still ongoing Thursday. The ICRC is not transporting prisoners of war to the places where they are held, according to a press release from the organization.
"The registration process that the ICRC facilitated involves the individual filling out a form with personal details like name, date of birth and closest relative," the organization said. "This information allows the ICRC to track those who have been captured and help them keep in touch with their families."
The Geneva-based humanitarian agency, which has been working in Ukraine since 2014, noted that it "maintains a confidential dialogue with the parties to the conflict on their obligations under international humanitarian law."
"In accordance with the mandate given to the ICRC by States under the 1949 Geneva Conventions, the ICRC must have immediate access to all POWs in all places where they are held," the organization added. "The ICRC must be allowed to interview prisoners of war without witnesses, and the duration and frequency of these visits should not be unduly restricted. Whenever circumstances permit, each party to the conflict must take all possible measures to search for and collect the dead."
For weeks, Ukrainian fighters and civilians were holed up inside Mariupol's vast Azovstal plant as the remaining pocket of Ukrainian resistance to Russia's relentless bombardment of the strategic southeastern port city. Russia claimed Thursday that 1,730 Ukrainian fighters had surrendered in Mariupol over the previous three days, while Ukraine confirmed Tuesday that more than 250 had yielded in the initial hours after it ordered them to do so.
Mariupol is the largest city that Russian forces have seized since launching an invasion of neighboring Ukraine on Feb. 24. Its complete capture gives Russia total control of the coast of the Sea of Azov as well as a continuous stretch of territory along eastern and southern Ukraine.
-ABC News' Max Uzol
Russia has fired senior military commanders in recent weeks "who are considered to have performed poorly during the opening stages of its invasion of Ukraine," the U.K. Ministry of Defense said Thursday in an intelligence update.
According to the ministry, Lt. Gen. Serhiy Kisel, who commanded Russia's elite 1st Guards Tank Army, has been suspended for his failure to capture Ukraine's second-largest city, Kharkiv. Vice Adm. Igor Osipov, who commanded Russia's Black Sea Fleet, has also likely been suspended following the sinking of the fleet's flagship, Moskva, in April. Gen. Valeriy Gerasimov, the Russian military's chief of the general staff, likely remains in his post, but it was unclear whether he retains the confidence of Russian President Vladimir Putin, according to the ministry.
"A culture of cover-ups and scape-goating is probably prevalent within the Russian military and security system," the ministry said. "Many officials involved in the invasion of Ukraine will likely be increasingly distracted by efforts to avoid personal culpability for Russia’s operational set-backs."
"This will likely place further strain on Russia's centralised model of command and control, as officers increasingly seek to defer key decisions to their superiors," the ministry added. "It will be difficult for Russia to regain the initiative under these conditions."
