"We are going to step up our efforts to deliver arms and ammunition-- this is a war of high intensity in which they play a crucial role," Breton said, citing a pledge to supply a million high-calibre weapons over the next 12 months.

"We are preparing for the war to last several more months, or even longer," he added.

Ukraine launched a counteroffensive earlier this month to retake territory from Russian forces, and U.S. Defense Secretary Lloyd Austin last Thursday urged Kyiv's allies to "dig deep" to provide more arms and ammunition.

(Reporting by Elizabeth Pineau and Mimosa Spencer; Editing by Hugh Lawson)