U.S. President Barack Obama and his Chinese counterpart Xi Jinping heightened hopes for resolving North Korea’s nuclear problem when they pledged to work together to denuclearize the recalcitrant regime during their summit in June. South Korean President Park Geun-hye’s meetings with the leaders of the two superpowers, which preceded and followed the Obama-Xi talks within a month, seemed to have helped consolidate the momentum toward the resolution of the issue that has threatened security on the Korean Peninsula and in Northeast Asia for decades.

As cautioned by some experts, however, the road to North Korea’s denuclearization still remains bumpy. With the North having taken no significant steps to demonstrate its sincerity, Washington and Beijing have been apart over whether to resume the six-party talks aimed at dismantling Pyongyang’s nuclear arsenal. The dialogue has been stalled since 2008.

China has said the multilateral discussion that also involves the two Koreas, Japan and Russia still remains an important platform to persuade North Korea to give up its nuclear programs and settle other relevant security issues. The U.S. has followed South Korea’s stance that it is meaningless to reopen the long-stalled talks unless North Korea shows a clear willingness to abandon its nuclear arms through concrete actions.

Seoul and Washington apparently want Beijing to put further pressure on Pyongyang to withdraw its demand for recognition as a nuclear power and return to credible and authentic negotiations aimed at its denuclearization. While having managed to push North Korea into being ready for the resumption of the talks, China seems to have had difficulty with getting its intractable neighbor to change its stance on denuclearization. Recent satellite images suggested that the North may have begun reactivating its nuclear reactor in Yongbyon.

In a move designed to make a breakthrough, Beijing recently proposed holding a gathering of officials and academics from nations involved in the six-party negotiations in Beijing next week. Seoul and Washington have also remained cautious on sending senior government officials to the informal forum.

The schism between the U.S. and China is worrisome as it could send the wrong signal to North Korea. The two superpowers should strengthen efforts to coordinate their stances on the multilateral framework for resolving Pyongyang’s nuclear problem.

Certainly, there is the possibility that the resumption of the six-party talks without verifying the North’s sincere attitude would only give it more time to further advance its nuclear programs while circumventing international sanctions. But the U.S. also seems too distracted by the crisis in Syria and domestic matters to actively take on the North Korean issue. At this juncture, Seoul may need to come forward to assume a more proactive role in pushing forward the process of settling the nuclear standoff with Pyongyang.