President Biden’s description of President Putin as a ‘worthy adversary’, in advance of their summit today, was a sensible move. On the one hand, it restores the basic civility necessary for any diplomatic exchange, after Biden’s unfortunate ‘killer’ remark. After all, the conduct of international relations by a superpower is a serious matter — and part of Biden’s own international prestige lies in his restoration of dignity to the US presidency after the flamboyant excesses of Trump.