Nuclear nightmare: reckless leaders are pushing the world back to the brink

Leaders of unstable nuclear-armed states do dangerous and foolish things when under stress. They miscalculate, provoke, overreach. Given the febrile state of bilateral relations, last week's aerial military clash between Russia and the US over the Black Sea inevitably intensified fears of nuclear escalation. The incident dramatised how dangerous Vladimir Putin, cornered by his existential Ukraine blunder, truly is - and the risks he is increasingly prepared to run. But he's not the only one. As often the case over the past year, Putin relied on American restraint. US forces could easily have gone after the offending Su-27 fighter at…