"We want, like you, a sovereign and prosperous Ukraine. But we must start by recognising that returning to Ukraine’s pre-2014 borders is an unrealistic objective," Hegseth told the meeting of Ukrainian officials and more than 40 allies.
"Chasing this illusionary goal will only prolong the war and cause more suffering," he added.
He also told Washington's NATO allies that they would have to step up and assume greater responsibility for Europe's security. He said "stark strategic realities", such U.S. border security issues and threats posed by China, prevented the U.S. from being "primarily focused on the security of Europe".
