Facing a mounting drumbeat of calls on Wednesday for stronger military action in northern Iraq, the British authorities have agreed to send a “small number” of Chinook helicopters and to transport military equipment supplied by other countries to Kurdish fighters in the American-led campaign against Sunni militants, officials said. But the government continued to insist that it was focused on humanitarian relief efforts, notably to get water and other supplies to thousands of Yazidis besieged on the arid, baking heights of Mount Sinjar, rather than on offering direct military involvement. In recent days, with many government leaders including Prime Minister David Cameron on vacation, Britain has slowly stepped up its relief effort, sending three Tornado warplanes on surveillance missions to support airdrops by C-130 military cargo planes. “Our focus remains the humanitarian situation, particularly those trapped on Mount Sinjar,” Mr. Cameron’s office said in a statement . […]