Idle since 2007, the North Korean government has resumed work at its Yonbyon nuclear facility, South Korea's Yonhap News Agency reported this week. The facility was shut down in exchange for food assistance and as a confidence-building step toward denuclearization.
Multilateral talks between the two Koreas, China, the United States, Russia and Japan stalled in 2009. North Korea in February conducted a nuclear test, its third since 2006.
Carter, a member the non-governmental organization The Elders, said talks are at a standstill.
"Ever since [President Barack] Obama has been in office, there has been no six-party talk and no real communication with North Korea," he said in an interview with Japan's political affairs magazine Chuo-Koron.
Washington said it wants nuclear assurances from North Korea before it sits down at the negotiation table. Carter, however, said few parties are interested in talking directly to Pyongyang.
"The biggest problem in the perpetuation of this threat to peace in that region is the unwillingness of others to talk to North Korea and to North Korean leaders," he said Tuesday.