South Korea, the U.S. and Japan, who have taken a tough stance against North Korea's provocations upped the pressure on Pyongyang this week. However, the different political agendas of the so-called six parties involved in talks to denuclearize the North seem to have become a stumbling block to progress. Choi You-sun has more. Earlier this week, the chief nuclear negotiators of South Korea, the U.S. and Japan were united in pressuring North Korea not to carry out a fourth nuclear test. "It would be a direct provocation to the international community and a grave threat to global peace and stability. We, along with the international community will make sure North Korea pays for it." The three nations together with China and Russia have tried to denuclearize the North for more than a decade, but each participating country's political interests have gotten in the way. Behind the three parties' unified voice, Seoul and Washington reportedly demanded Tokyo's transparency in its recently revived two-way dialogue with Pyongyang. The Abe administration is determined to get answers from the North about its abductions of Japanese nationals during the 1970s and 80s. North Korea's traditional ally China, which wants unconditional dialogue resumption with Pyongyang, is urging the other three parties to be more prudent in their choice of words or actions. In keeping check of each other's military dominance in the Asia-Pacific this week, the U.S. and China, both key members in resolving the nuclear issue, are engaged in a war of words over China's territorial claims in the region. With cracks appearing in relations among the six-party members, analysts say the six-party's handling of North Korea will likely depend on Washington and Beijing's level of cooperation. Choi You-sun, Arirang News.