The UN's chief nuclear inspector played down expectations Monday that his trip to North Korea heralded the communist country's rapid disarmament, saying a build up of trust and confidence were needed first. Mohamed ElBaradei, head of the Vienna-based International Atomic Energy Agency, stopped in Beijing on his way to North Korea for discussions on how to implement a landmark nuclear disarmament agreement reached at six-nation talks last month. "I should caution that is a very complex process," ElBaradei told reporters at the airport. "It is going to be a very incremental process. There's a lot of confidence that needs to be built."