North Korea was poised to take its first step toward scaling back its nuclear weapons program in nearly five years as UN inspectors prepared to embark on a mission to monitor Pyongyang shutting down its sole operating atomic reactor. The team from the International Atomic Energy Agency stopped in Beijing en route to the North, with its Saturday arrival in Pyongyang scheduled just hours after a South Korean oil shipment was to enter a North Korean port - a promised reward for the reactor shutdown pledge. The South Korean tanker No. 9 Han Chang - carrying 6,200 tons of heavy fuel oil - was near the North's northeastern port of Sonbong on Saturday morning, waiting for a North Korean permission to dock, a Unification Ministry official said. The official spoke on condition of anonymity.