More than three months after Secretary of State Michael Pompeo picked Stephen Biegun to lead negotiations with North Korea, the former Ford Motor Co. executive has barely met officials from Pyongyang face-to-face.

The standstill is a sign of how negotiations between the U.S. and North Korea have faltered, forcing a lowering of expectations, since President Donald Trump met with Kim Jong Un in Singapore in June. Biegun was appointed in August to help follow up on the opening created by the summit, but North Korean officials have ignored Pompeo's invitation in September to meet with Biegun "at the earliest opportunity."

Kim's regime may feel emboldened to spurn the usual channels of diplomacy because Trump has emphasized his personal rapport with the autocratic leader and his interest in holding a second summit soon, according to current and former administration officials.