Russia has “nothing to celebrate” on Victory Day, despite attempts by Moscow to demonstrate that it is winning the war in Ukraine, U.S. Ambassador to the U.N. Linda Thomas-Greenfield told CNN on Sunday.

The Russians “have not succeeded in defeating the Ukrainians. They have not succeeded in dividing the world or dividing NATO,” Thomas-Greenfield said. “They have only succeeded in isolating themselves internationally and becoming a pariah state around the globe. So what they’re celebrating tomorrow is their own lack of success.”

Russia is set to mark on Monday Victory Day, which celebrates the country's part in the Allied victory over Nazi Germany in World War II.

The ambassador stressed that “the Russian government invaded Ukraine. They started this war. They are attacking the Ukrainian people. And we have been consistent since the start that we will support Ukraine. We will provide them with the wherewithal to fight this war,” adding that Moscow has “felt the consequences of our support for the Ukrainians.”

Thomas-Greenfield reiterated that the United States is providing the Ukrainian government “with the intelligence so that they can defend themselves against Russian aggression and also put them in a position where they’re stronger at the negotiating table against the Russians.”

When asked about reports that the Russians killed dozens of civilians over the weekend when their forces bombed a school that housed Ukrainians sheltering from the war, Thomas-Greenfield said that “we have called out the Russians very early on for committing war crimes and this contributes to that."

She emphasized that "we are going to continue to work with the Ukrainian prosecutors and others to document evidence of their war crimes so that they can be held accountable. This just adds to the long list that we already have.”

• Biden, G7 Leaders Pledge Further Economic Isolation of Russia
• Dozens Feared Dead as Russian Shell Hits Ukrainian School