Timing, the old adage goes, is everything, and in attempting to peel back the thick layer of mystery surrounding North Korea's nuclear intentions, the timing of its decision to follow through on its long-standing invite for a top United Nations official to visit may offer insight into a renewed diplomatic push or mediator role for the U.N., experts say.

Pyongyang formally extended the invitation to Jeffrey Feltman, the U.N.'s political chief — and America's highest-ranking national in the U.N. Secretariat — on Nov. 30, just a day after successfully testing its most powerful long-range missile and declaring its quest for nuclear weapons effectively complete.

That invitation had been informally delivered to Feltman during the annual gathering of world leaders at the General Assembly in September, according to U.N. spokesman Stephane Dujarric, presumably by North Korean Foreign Minister Ri Yong Ho, who had attended the session.