A White House official made two secret visits to North Korea last year in an unsuccessful effort to improve relations after Kim Jong-un assumed power, according to former US officials familiar with the trips.
The brief visits in April and August were aimed at encouraging the new leadership to moderate its foreign policy after the death of Kim's father, Kim Jong-il, in December 2011.
The ruling elite apparently spurned the outreach effort. This month, after a surge of fierce anti-US rhetoric, the government in Pyongyang defied international warnings and conducted its third and most powerful underground nuclear test.
The former US officials said the first visit was an unsuccessful attempt to persuade North Korea not to launch a long-range rocket. North Korea carried out the launch on April 12. The missile flew only a few minutes before it exploded and crashed into the sea. A subsequent test of another long-range rocket in December was successful.
The April trip was led by Joseph DeTrani, an expert on North Korea who then headed the National Counter Proliferation Centre in the Office of the Director of National Intelligence, which co-ordinates US intelligence agencies, the former US officials said. It was unclear who led the August trip.
They said Sydney Seiler, who is in charge of Korea policy at the National Security Council, went on both trips. Seiler, a veteran CIA analyst, speaks fluent Korean.
The White House, State Department and CIA have refused to confirm or deny the 2012 trips, which occurred during the US presidential election season.
US officials have visited North Korea on and off for years. They include secretary of state Madeleine Albright, who led an official state visit in 2000. The last official US visit was in 2009 when US special envoy Stephen Bosworth sought to restart stalled six-party negotiations on North Korea's nuclear programme. The talks have not resumed.
Without confirming the 2012 trips, DeTrani said it "makes eminent sense" for the United States to conduct talks with North Korean officials after Kim Jong-il's death. DeTrani said he and other US experts initially saw signs that Kim Jong-un might behave less rigidly than his father, including putting moderate figures in key government positions.
Those hopes were quickly dashed, however. In addition to the rocket launches and nuclear test, the new leader appointed a defence minister, General Kim Kyok-sik, who reportedly was responsible for the 2010 shelling of a South Korean island that killed four people, and the sinking of a South Korean naval ship that killed 46 sailors.
"I was initially guardedly optimistic that [Kim Jong-un] was moving in the right direction," DeTrani said. "With the launches and the test, he's reversed that."