Is it ageist to suggest that an obviously frail 80-year-old might not be well suited to the task of resolving global conflicts? Even a man in his prime would struggle to fly from Washington to Israel, do a frantic day of talks, greet the suffering, make a speech and jet off again hours later to go back to leading the free world.

Joe Biden is not, to put it mildly, a man in his prime. The octogenarian Commander-in-Chief just about got through his duties in the Holy Land. He delivered a passable, albeit platitudinous speech about dealing with the pain caused by terrorism.

But then he reappeared in front of reporters on Air Force One, and the world was duly given another distressing Biden cognitive failure episode.

The President looked utterly shattered in his blue zipped retirement sweater. He appeared to be struggling with his balance. And couldn’t really talk at all.

Biden remarked that Hamas ‘gotta learn to shoot straight’ – an extraordinarily clumsy and flippant reference to the bombed out hospital in Gaza. This qualifies as a classic Biden gaffe: in trying to show his support for the Israeli position that Hamas, not the Israeli Defence Force, were responsible for Tuesday night’s atrocity, he somehow managed to suggest that all would be well if only Hamas were better at successfully aiming their rockets at innocent Israelis. Just days after Hamas managed to kill 700 Israelis.

All presidents make gaffes: George W Bush was a master of the rhetorical flub, Donald Trump said many crazy things and even smooth-talking Barack Obama had the odd slip. The bigger concern with Biden, however, is not that he misspeaks so often, but that he increasingly cannot really speak at all.

Nobody should mock the elderly, but polls suggest the American public is seriously concerned about Biden’s health. If he staggers on to win next year’s presidential election, does anybody really expect him to make it through another four years?