Russia-Ukraine updates: US sanctions Russian military shipbuilder, diamond miner

Save the Children is calling for an immediate ban on intercountry adoptions of children uprooted by Russia's invasion of Ukraine to protect them from human traffickers or child abusers.

The international children's charity warned in a statement Tuesday that "during mass movement of refugees, well-meaning people may attempt to 'rescue' children from the crisis-affected area in the mistaken belief that they will be better cared for in other environments." But Save the Children stressed that "the best place for children is with their families and communities, and adoption is not an appropriate response for unaccompanied children until authorities and agencies have made all efforts to trace and reunite them with their families."

The organization also warned that "not everybody attempting to foster or adopt children from Ukraine does so with the best intentions."

Save the Children is calling on states to support a moratorium on all adoptions "until appropriate safeguards are in place" for the unaccompanied children who have fled Ukraine as well as those who have been uprooted within the country. Ukraine has suspended its intercountry adoption program until further notice in the wake of the ongoing war. But Save the Children noted that "it is important for receiving countries to also suspend intercountry adoption proceedings to ensure the appropriate international standards and safeguards."

Save the Children staff in Romania have reported seeing some kids arriving from Ukraine unaccompanied, while others have been separated from their families in the chaos of fleeing their homes. The organization said many are under 14 and showing signs of psychological distress.

"There is so much upheaval in a child’s life during this time that the best place for them is with their families, relatives, and communities, rather than being removed to a foreign country and language. The most protective environment for a child is the safety and stability of their own family," Amanda Brydon, global head of child protection advocacy for Save the Children, said in a statement. "At this stage of this crisis, an immediate moratorium on intercountry adoptions is critical to ensure that children are safe and that where possible and in their best interests, they are reunited with their caregivers or verified family members. Sending funds to trusted humanitarian agencies for their response to this crisis is one of the best ways to be able to support such children currently."

The U.S. Department of State announced Tuesday that it has coordinated with St. Jude Children's Research Hospital "to provide necessary life-saving and immediate care to four Ukrainian children whose ongoing cancer treatment was disrupted" by Russia's invasion of Ukraine.

The State Department helped airlift these pediatric cancer patients and some of their immediate family members from Poland to the international airport in Memphis, Tennessee, where they were subsequently transported to St. Jude Children's Research Hospital.

"There, the patients will be able to safely resume critical cancer therapy disrupted by the Kremlin’s aggression," State Department spokesperson Ned Price said in a statement. "They will receive the specialized care they desperately need, and their family members will be afforded sustenance, security, and support from St. Jude."

Over 3.5 million people have fled Ukraine since Russian forces invaded on Feb. 24, and more than half went to neighboring Poland, according to the latest figures from the United Nations refugee agency.

"Children are among the most vulnerable in a crisis, and these pediatric oncology patients need urgent and highly specialized medical care. We are proud to stand with European partners who are also treating children whose life-saving care in Ukraine has been made impossible by Putin's war," Price added. "We recognize, however, that the children transported represent a small proportion of the thousands of patients whose cancer treatment has been interrupted and, who, even amid a pandemic and with compromised immune systems, were forced to flee their homes. That is why, together with our allies and partners, we will continue to support our Ukrainian partners as we seek to save lives and bring this needless war to a close."

-ABC News' Conor Finnegan

Russian journalist Dmitry Muratov announced Tuesday that he and independent Russian newspaper Novaya Gazeta have decided to auction off their 2021 Nobel Peace Prize Medal and donate the proceeds to the Ukrainian Refugee Fund.

"There are already over 10 million of refugees," Muratov wrote on the Novaya Gazeta website, "I ask the auction houses to respond and put up for auction this world-famous award."

Muratov is the editor-in-chief of Novaya Gazeta and won the 2021 Nobel Peace Prize with journalist Maria Ressa.

Russian troops fired gas into a crowd of peaceful protesters in the southern Ukrainian city of Kherson on Tuesday.

Video from the scene, taken by journalists, shows projectiles landing in a square in central Kherson where residents had gathered to protest Russia's occupation of the city. Loud bangs can be heard and the crowd suddenly disperses as people attempt to flee the smoke and gas emitting from the canisters around them. People are seen coughing and covering their faces as they run away.

-ABC News' Julia Drozd and Fergal Gallagher