ith the allied premiers now in discussion at Nato’s Vilnius Summit, the assembled countries would no doubt like to be in a common position that projects unity, strength and strategic clarity. Instead, the western alliance finds itself in disagreement. Sweden’s Nato accession has been settled by a bit of horse-trading by President Biden, but Ukraine’s path to future accession and the new defence investment pledge are up in the air. If these issues are not clearly and successfully addressed in Vilnius, then many will consider this Summit a failure. Most likely the Alliance will overcome the political disagreements, have a...