China has dropped a "Cold War" mentality a long time ago in dealing with thorny issues on North Korea, a Chinese military professor said Wednesday, urging that both Seoul and Beijing must deepen bilateral relations to promote peace and stability on the Korean Peninsula.

"Long gone are the Cold War days when China was inclined to engage with the DPRK (North Korea) and estrange itself from the ROK (South Korea)," Ouyang Wei, a professor at the National Defense University of the People's Liberation Army, wrote in an op-ed published by the state-run China Daily.

Ouyang said China is trying to balance relations with its key ally North Korea and its major trading partner South Korea.

The remarks came at a time when China's leadership is reportedly dissatisfied with the unruly North Korea, which last month purged leader Kim Jong-un's once-powerful uncle, Jang Song-thaek, in a stunning execution. South Korea and the U.S. have kept a close watch on North Korea amid fears that the young Kim may carry out provocations to forge internal unity following the political upheaval.

China has also become increasingly frustrated with North Korea's nuclear weapons ambition, particularly after the North's third nuclear test in February last year.

"Today, China is seeking friendly relations with the two peninsula countries based on mutual respect, mutual benefit and win-win outcomes," Ouyang said.

"At a time when there is no quick fix to the peninsula issue and the DPRK's nuclear program, the deepening China-ROK ties carry significant weight in promoting peace and stability on the peninsula," the professor said.

"The desire for denuclearization of the peninsula, in addition to the common interests of Beijing and Seoul, lays a solid foundation for deepening bilateral relations," Ouyang said.

Jang was executed on Dec. 12 on charges of treason, corruption and other misdeeds. Jang was also accused of selling the North's coal to a foreign country at excessively cheap prices.

The execution marked the biggest political upheaval since Kim took power two years ago and raised concerns for North Korea's economic ties with China, as Jang had overseen key business projects with Beijing. (Yonhap News)