US President Donald Trump is expected to claim he is winning both on the battlefield and as a peacemaker Tuesday in a speech to the United Nations overshadowed by growing spillover from his stalled war against Iran.

Trump will likely not hold back in renewing his frequent boasts that under him the United States is "the hottest country" in the world.

He is also expected to seek to justify the Iran war, which has so far failed to fulfil White House objectives and provoked widespread economic damage over the Strait of Hormuz's closure.

But the self-styled peacemaker could equally use the UN stage to tout his controversial efforts to end the Gaza conflict and his ongoing effort to bring more Arab countries into the Abraham Accords with Israel.

"No one knows what Trump is going to say, not even Trump's speechwriters," International Crisis Group's Daniel Forti said.

"This year, we expect more of a cont...