Top U.S. nuclear negotiator Sung Kim says that even if North Korea declares its return to the six-party nuclear talks, the multilateral dialogue will not resume until the investigation into the sinking of the South Korean “Cheonan” warship is completed.

Kim, the U.S. chief delegate to the six-way talks, made the remark at the annual Seoul-Washington Forum held in Washington Wednesday, putting top priority on determining the cause of the maritime incident.

Kim was also quoted as saying that if North Korea's involvement in the sinking is confirmed, the five parties of the six-way talks excluding the North will discuss response measures including the future of the nuclear dialogue.

Principal Deputy Assistant Secretary of Defense for Asian and Pacific Security Affairs Derek Mitchell also said in the forum that the Cheonan investigation must come before the six-way nuclear talks.