The US official said that why Ukraine would blast dam on its own territory.
The United States said on Tuesday it was "not certain" who was to blame for a burst dam in Ukraine, but it would not make sense for Ukraine to have done this to its own people and territory, as Kyiv and Moscow blamed each other for the disaster.
The 15-member U.N. Security Council met on Tuesday at the request of both Russia and Ukraine after a torrent of water burst through a massive dam on the Dnipro River that separates the opposing forces in southern Ukraine.
When asked if the United States knew who was responsible, Deputy U.S. Ambassador to the United Nations, Robert Wood, told reporters ahead of the council meeting: "We're not certain at all, we hope to have more information in the coming days."
"But, I mean, come on ... why would Ukraine do this to its own territory and people, flood its land, force tens of thousands of people to leave their homes - it doesn't make sense," Wood said.
U.N. Secretary-General Antonio Guterres said earlier on Tuesday that the world body did not have any independent information on how the dam burst, but described it as "another devastating consequence of the Russian invasion of Ukraine."
Many Security Council members also asserted during Tuesday's meeting that the crisis would not have occurred if Russia had not invaded neighboring Ukraine in February last year.
Russia's U.N. Ambassador Vassily Nebenzia blamed Ukraine, without providing evidence, accusing it of trying to create "favourable opportunities" for it to regroup its military units to continue a counter offensive.
"The deliberate sabotage undertaken by Kyiv against a critical infrastructure facility is extremely dangerous and can essentially be classified as a war crime or an act of terrorism," Nebenzia told the council.
Ukraine's U.N. Ambassador Sergiy Kyslytsya accused Russia of a "terrorist act against Ukrainian critical infrastructure," without providing evidence.
"It is physically impossible to blow it up somehow from the outside by shelling - it was mined by the Russian occupiers and they blew it up," Kyslytsya said.
U.N. aid chief Martin Griffiths told the Security Council that "the sheer magnitude of the catastrophe will only become fully realized in the coming days."
"But it's already clear that it will have grave and far-reaching consequences for thousands of people in southern Ukraine on both sides of the front line through the loss of homes, food, safe water and livelihoods," he added.
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