NATO SECRETARIES-GENERAL do not normally attack the policies of the alliance’s biggest and most important member country. But Jens Stoltenberg, whose ten-year stint in charge is coming to an end, has done just that. In an interview with The Economist on May 24th, he called on NATO allies supplying weapons to Ukraine to end their prohibition on using them to strike military targets in Russia. Mr Stoltenberg’s clear, if unnamed, target was the policy maintained by Joe Biden, America’s president, of controlling what Ukraine can and cannot attack with American-supplied systems.