David Cameron, the British prime minister, led the attack: It would be “unthinkable” for the British to sell a warship to Russia, he declared. Almost immediately, the French president, François Hollande, confirmed his intention to do precisely that: He would, he said, deliver a Mistral amphibious assault ship to the Russian navy, as contracted — and then he hit back hard. “This is a false debate led by hypocrites,” one of his party colleagues declared. “When you see how many [Russian] oligarc...