The annual ASEAN Regional Forum has opened in Singapore.

Foreign ministers of Southeast Asian nations on Tuesday launched discussions on pending security issues including the North Korean nuclear issue.

Foreign ministers of countries participating in the six-party talks will hold a meeting Wednesday on the sidelines of the forum.

South Korea’s top nuclear envoy Kim Sook and his U.S. counterpart Christopher Hill held a preliminary meeting Tuesday.

After the meeting, Kim said that North Korea has received a proposal from the United States for verifying the North's claim about its nuclear past.

In addition, Kim and Hill reportedly discussed the shooting death of a South Korean tourist at the North’s Mount Geumgang resort.

Hill reportedly said that Pyongyang should cooperate with the investigation as soon as possible.