Those who believe Trump colluded with Russia in the 2016 election argue that the Steele dossier may be correct — that Moscow does have compromising information about the President’s past, that it can use as leverage over him.

Another possible explanation is that Trump is digging in his heels because he sees any criticism of his approach to Russia as bound up in the election meddling issue, that he has blasted as a hoax designed to invalidate his shock White House victory.

Putin meanwhile is one of the group of autocrats and global strongmen that Trump seems to admire — an odd quirk in an American President who often appears tougher on allies than US foes.