Arguments in the foothills of war are always the same. Those for war shout loudest and beat their chests, eager for tanks to rumble and jets to roar. The visit to Taiwan of the US congressional speaker, Nancy Pelosi, has been so blatantly provocative it seems little more than a midterm election stunt. A similar ambiguity infuses the west’s attitude towards Russia over Ukraine. The US and Britain reiterate that Russia “must fail and be seen to fail”. But can Russia really be relied on to tolerate ever greater destruction of its armaments without escalation? The west is blighted by...