As Russia provokes Europe with drones, jets, and strikes on tankers, and is the prime suspect in the bombing of a Polish train, it is becoming increasingly likely that Nato will have to act, warns world affairs editor Sam Kiley On The Ground newsletter: Get a weekly dispatch from our international correspondents Get a weekly dispatch from our international correspondents Get a weekly international news dispatch Email * SIGN UP I would like to be emailed about offers, events and updates from The