NATO chief Jens Stoltenberg urged leaders of the transatlantic security alliance on Tuesday to maintain support for Ukraine in its war against Russia’s invasion, declaring that the outcome of the conflict would shape global security for decades.

At the start of a summit in Washington to celebrate NATO’s 75th anniversary, Stoltenberg said the alliance had to show the same determination it had displayed at other key moments in its history.

“There are no cost-free options with an aggressive Russia as a neighbor. There are no risk-free options in a war,” he said. "The biggest cost and the greatest risk will be if Russia wins in Ukraine,” he added. “We cannot let that happen.”