WASHINGTON, Jan 15 (Reuters) - Advisers to President-elect Donald Trump now concede that the Ukraine war will take months or even longer to resolve, a sharp reality check on his biggest foreign policy promise - to strike a peace deal on his first day in the White House.

Two Trump associates, who have discussed the war in Ukraine with the president-elect, told Reuters they were looking at a timeline of months to resolve the conflict, describing the Day One promises as a combination of campaign bluster and a lack of appreciation of the intractability of the conflict and the time it takes to staff up a new administration.

Those assessments dovetail with remarks by Trump’s incoming Russia-Ukraine envoy, retired Lieutenant-General Keith Kellogg, who said in an interview with Fox News last week that he would like to have a “solution” to the war within 100 days, far beyond the president-elect’s original timeline.