The idea of Seoul and Washington imposing their own sanctions against Pyongyang will be one of the topics for the Thursday talks in Seoul between Glyn Davies, Washington's special representative for North Korea Policy, and South Korea's chief nuclear envoy Lim Sung-nam.
Davies is due to arrive in Seoul on Wednesday after the U.N. Security Council ordered new sanctions against North Korea's December rocket launch and vowed to take an unspecified "significant action" if the North carries out another rocket launch or a nuclear test.
"We have been in discussions with the U.S. side about additional bilateral sanctions against the North following the U.N. resolution," the diplomat said on the condition of anonymity.
Possible options would include making it more difficult for North Korean ships to travel in waters near the Korean Peninsula and strengthening inspections of North Korean ships suspected of engaging in weapons trafficking in accordance with U.N. sanctions, the diplomat said.
South Korea has also been "in negotiations with other relevant countries about additional bilateral sanctions against North Korea," the diplomat said.
In a swift response to the U.N. resolution, North Korea's foreign ministry threatened to strengthen its "nuclear deterrence," in an indication that it could conduct another nuclear test.
The diplomat said South Korea has been monitoring activities at a possible nuclear site in North Korea to determine if the North's third nuclear test is imminent, but said that "so far there has been no imminent sign of a nuclear test," adding that they are taking precautions and will be prepared to deal with all possible situations.
North Korea has been under U.N. sanctions since 2006 when it conducted its first nuclear test. The sanctions were tightened in 2009 after its second nuclear test.
Later Wednesday, Seoul's foreign ministry spokesman Cho Tai-young said South Korea will "review bilateral measures against North Korea with relevant countries while focusing on implementing the U.N. resolution."
Cho labeled the North's indication of a nuclear test as "very regrettable," while South Korea is closely monitoring activities at the North's nuclear test sites.
The spokesman also ruled out a meeting between Davies and South Korean President-elect Park Geun-hye.