A number of experts think the U.S. should abandon its “top down” strategy of building an Afghan national army and should switch to arming and paying local tribes to fight the Taliban. Former national security adviser Zbigniew Brzezinski, appearing Thursday at a Capitol Hill conference sponsored by RAND, said he closely examined former Soviet counterinsurgencies in Poland and the Ukraine. In both cases, the Soviets successfully levered small, locally recruited militia forces to successfully battle numerically superior anti-regime insurgents. He warned of the perils of trying to police xenophobic Tajiks, Uzbeks and Pahstuns with an Afghan national army. A better...