ISTANBUL Pakistani President Asif Ali Zardari on Saturday described the country’s defense as "impregnable" as the South Asian nation marked its 60th Defense and Martyrs Day. The professionalism, fighting skills, and war readiness on land, in the air, and at sea, of Pakistani army "assured us that Pakistan’s defense is impregnable as it is backed by the undying spirit of its people, and the unwavering resolve of its Armed Forces," Zardari said in a statement. Held annually on Sept. 6, Defense