BEIJING, April 3 (Reuters) - China hopes that a planned meeting between the leaders of North Korea and the United States in May can advance smoothly and that all sides maintain focus and avoid "disruptive factors", senior Chinese diplomat Wang Yi said on Tuesday. China has traditionally been secretive North Korea's closest ally but ties have been frayed by Kim's pursuit of nuclear weapons and missiles and Beijing's backing of tough UN sanctions in response. Wang, a State Councillor and China's Foreign Minister, said there had been positive changes on the peninsula and that all sides were engaging in "sincere exchanges". "China hopes all sides can maintain the momentum of contact and dialogue, and create conditions to smoothly restart dialogue," Wang said during a joint news briefing with visiting Swiss Foreign Minister Ignazio Cassis. Wang said he hoped the meeting between North Korean leader Kim Jong Un and U.S. President Donald Trump would "increase mutual understanding". "But historical experience tells us that at the moment of easing of the situation on the peninsula and as first light dawns on peace and dialogue, frequently all manner of disruptive factors emerge," Wang said. "So we call on all sides to maintain focus, eliminate interference, and firmly follow the correct path of dialogue and negotiation."
