A South Korean newspaper is claiming that a group of U.S. officials took an undercover trip to Pyongyang back in August, the second "secret" diplomatic meeting they've allegedly held in North Korea this year. The report seems to be based almost entirely on air traffic control data (via a "diplomatic source"), that supposedly proves that a U.S. Air Force plane took of from Guam on August 17, landed in Pyongyang, and returned four days later. The flight plan was over South Korean airspace, forcing the U.S. to notify officials in Seoul in advance, as well the Chinese.
Earlier this year, there was talk of a similar plane trip that took place back in April, but only lasted one day. Both flights happened shortly before North Korea had planned public missile tests, leading to speculation that the Americans were working to avoid any military provocations during the U.S. election season. (The launch on April 12 turned out to be an embarrassing failure.) In October, North Korea itself appeared to confirm that April meeting, saying that they had met with "Senior policy makers in the National Security Council and the Central Intelligence Agency," but only brought it up to prove that U.S. overtures for peace were a sham. The visit may have also been part of a food aid deal brokered by the U.S. in March, but then blocked after the April launch.
The other signal that may not just be wishful thinking is that after rumors of the April meeting first surfaced, State Department officials offered a classic "non-denial denial," simply saying they had no comment or no information to give. They gave the same answer to South Korean news services this time around. The two nations are officially incommunicado right now, but the notion of secret behind-the-curtain talks isn't that far-fetched. Though given the rumblings about yet another North Korean missile launch this week and the hiring of a new hardline defense minister, they don't appear to be doing much good.