Russia on Thursday reprimanded the head of the UN children’s agency UNICEF for not providing a “weighty argument for her refusal” to brief the Security Council on children in Gaza - a meeting requested by Russia.

Russia’s UN Ambassador Vassily Nebenzia said UNICEF Executive Director Catherine Russell, an American, had briefed the 15-member council on children in Ukraine “at the drop of a hat” in December, during the US presidency of the council.

“So it would appear that for UNICEF children in Gaza are less important than children in Ukraine,” Nebenzia said.

Russia invaded neighboring Ukraine in February 2022 and has been at war since then. The war in the Gaza Strip between Israel and Palestinian militants Hamas began in October 2023 and a ceasefire took effect on Sunday.

“The refusal of UNICEF’s head to brief the Security Council about the horrific tragedy linked to the death of tens of thousands of children in Gaza is a flagrant step, which deserves our most serious censure,” Nebenzia told the council.

Russell is at the World Economic Forum in Davos, Switzerland with a focus on addressing humanitarian crises and was unable to adjust her schedule to brief the Security Council, said a UNICEF spokesperson.

“Ms. Russell had offered the Director of Emergencies to deliver her statement on her behalf,” the UNICEF spokesperson said. “The UNICEF Executive Director has briefed the Security Council several times on the situation of children in Gaza and appreciates the council’s focus on children impacted by war.”

The Security Council has met dozens of times to discuss the war in Gaza. Israel’s armed and security forces, Hamas and Islamic Jihad militants, and Russia’s armed forces are all on the UN global list of offenders for killing and maiming children.

Nebenzia also accused Washington on Thursday of some responsibility for the deaths of children in Gaza after the US used its council veto to shield Israel during the war. He also said the US ignored Russian calls for a meeting on Gazan children in December.

Acting US Ambassador Dorothy Shea rejected Nebenzia’s accusations.

“The idea that the United States is responsible for the terrible suffering there is just unacceptable to us and we reject it in its totality,” she told the council.

UN aid chief Tom Fletcher briefed the Security Council meeting on Thursday via video from Stockholm. He bluntly assessed the past 15 months of war in Gaza: “Children have been killed, starved, and frozen to death.”

“They have been maimed, orphaned, separated from their family. Conservative estimates indicate that over 17,000 children are without their families in Gaza,” he said. “A generation has been traumatized.”

Under the ceasefire, the United Nations and others are carrying out a surge of humanitarian aid into Gaza.