Russian downing of US drone marks escalation of confrontation near war zone

Russia's and China's signalling' to US aircraft in international airspace is nothing new, but downing a craft is a worrying development

On any given day around Ukraine's Black Sea coast, Russian and Nato aircraft and naval vessels, manned and unmanned, buzz around in close proximity, a constant recipe for a superpower crisis along the edges of a war.

The stakes are raised by the fact that both sides have thousands of nuclear warheads as a weapon of last resort, and the risks are raised considerably by reckless behaviour.