Jens Stoltenberg, Nato’s secretary- general since 2014, knows the importance of a measured response. When we meet in central Brussels, less than 72 hours after a missile had exploded in the Polish village of Przewodów, close to the Ukrainian border, he looks understandably exhausted. In the immediate aftermath of the explosion on 15 November, which killed two Polish farmers, many feared the worst. ?ukasz Jasina, a Ministry of Foreign Affairs spokesperson for Poland – a Nato member since 1999 – released a statement calling the missile “Russian-made”; Ukraine’s president, Volodymyr Zelensky, said in his nightly televised address: “Russian missiles hit...