South Korea is ratcheting up diplomatic efforts with the U.S. and China amid growing uncertainty surrounding North Korea following the execution of leader Kim Jong-un’s uncle.

Seoul’s Foreign Minister Yun Byung-se plans to travel to Washington next week for talks with U.S. Secretary of State John Kerry and other ranking officials.

With Pyongyang’s nuclear program topping the agenda, the two top diplomats are also expected to trade views regarding the situation on the peninsula in the wake of the purge of Jang Song-thaek, former vice chairman of the National Defense Commission and once considered the communist state’s second-in-command.

“My planned visit would serve our pursuit of strategic, preemptive diplomacy and help us size up the circumstances surrounding the peninsula and North Korea for the new year,” Yun told reporters.

The trip comes shortly after Yun’s one-hour phone conversation with Chinese Foreign Minister Wang Yi on Dec. 31. They discussed the North Korea situation and agreed to continue strategic cooperation for “substantive progress” in its denuclearization.

Wang is forecast to come to Seoul this year, while the two countries are seeking to hold a vice-minister-level strategic dialogue as early as this month.

The two latest consultations marked the first top-level exchanges since the purging of Jang, whose death fueled concerns over the instability of Kim’s 2-year-old regime and a possible provocation to cope with it.

In a fresh twist, the young, unpredictable leader launched a peace offensive in his New Year’s address Wednesday. He called on the South to “come forward” to improve relations with the North, while vowing to do his part for the cause.

Seoul remains cautious, however, warning of “deepening uncertainty and fluidity” driven by Jang’s demise.

“We ought to pay great attention to the impact of Jang Song-thaek’s execution not only on the possibility of a North Korean provocation, but also on the Kim Jong-un regime, the nuclear issue and its relations with neighbors,” Yun said in his own New Year’s speech to the ministry officials on Thursday.

Another pressing issue is heightened tension in Northeast Asia in the wake of Japanese Prime Minister Shinzo Abe’s much-criticized visit to the controversial Yasukuni war shrine last week.

Seoul and Beijing condemned it as an attempt to whitewash Tokyo’s imperial past and colonial rule, whereas Washington expressed “disappointment,” warning of further tensions with Japan’s neighbors.

But South Korea appears to be refraining from giving a sign that it has joined hands with China for any joint action over historical issues, possibly in consideration of its future ties with Japan and trilateral cooperation involving the U.S., a staunch ally of Seoul and Tokyo.

Japan, for its part, is seen to be ramping up efforts to contain mounting criticism and turn the tide in its favor. Shotaro Yachi, Abe’s special adviser and the inaugural head of Tokyo’s National Security Council secretariat, is reportedly scheduled to visit Washington this month.

“Though those in and around Washington see Abe’s worship at Yasukuni as a grave misjudgment, I think for us it’s more important not to overplay our hand but show the attitude of a mature diplomatic partner,” a Seoul official said on condition of anonymity.

By Shin Hyon-hee (heeshin@heraldcorp.com)