U.S. intelligence expects the reduced tempo in fighting in Ukraine to continue in the next several months and sees no evidence of a reduced Ukrainian will to resist, despite attacks on its power grid and other critical winter infrastructure, the Director of National Intelligence said on Saturday.

"We're seeing a kind of a reduced tempo already of the conflict ... and we expect that's likely to be what we see in the coming months," Avril Haines told the annual Reagan National Defense Forum in California.

She said both the Ukrainian and Russian militaries would be looking to try to refit and resupply to prepare for a counteroffensive after the winter, but there was a question as to what that would look like.