Bangladesh, Oct. 2 -- When US President Donald Trump declared after meeting Ukrainian President Volodymyr Zelensky at the UN General Assembly that a “total return of land lost to Russia” was possible, much of the West briefly exhaled. After years of stalemate, mounting war fatigue, and skepticism about Washingtons wavering role, this sounded-at least superficially-like a renewed American commitment. But beneath the rhetoric lay the same contradictions and uncertainties that have plagued the Western approach to Ukraine since the war began.

Trumps declaration, made through a social media post, was quickly seized upon by Moscow. Russian officials suggested he was parroting Zelenskys words, casting Trump as being manipulated by K...