South Korean President Park Geun-hye on Wednesday urged China to help ensure that North Korea feels “pain” over its recent nuclear test as the international community looks to Beijing to exert its significant influence over Pyongyang.

Tensions are running high on the Korean Peninsula after the test last week, with propaganda volleys across the tense border between the two Koreas and shots fired Wednesday after a Northern drone briefly flew into Southern airspace.

With the U.N. Security Council looking to punish Pyongyang for its latest provocation, Park made it clear that Beijing holds the key.

“We will make every effort for the strongest sanctions against North Korea by taking new actions. China’s role is significant here,” she said during a rare news conference. “A true partner offers a helping hand in difficult times. We believe China will play its role as a permanent member of the U.N. Security Council.”

[Reported North Korean nuclear test signals snub of China, fraying ties]

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China, the closest thing North Korea has to a friend, has previously used its veto power to ensure that multilateral sanctions are not so severe as to cause its fragile neighbor to collapse, although Beijing did allow a significant expansion of sanctions after Pyongyang’s 2013 nuclear test.

Chinese President Xi Jinping has made little secret of his disdain for Kim Jong Un, the young North Korean leader, and critics of North Korea hope that Beijing will be sufficiently angry this time around to support even tougher sanctions.

“Sanctions are useless unless they cause pain and bring about changes in North Korea,” Park told a select group of reporters at her New Year’s news conference. “The international community’s response to the North Korean nuclear problem this time must be different from the past.”

Relations between China and South Korea have steadily improved under Park and Xi, who has visited the South but not the North. But Beijing has maintained its trade ties and aid delivery to North Korea so its nuclear-armed neighbor maintains its stability.

The Security Council is formulating a new round of sanctions, while the United States also looks for ways to ratchet up the pressure on North Korea to relinquish its nuclear program. The White House has vowed to “isolate” Pyongyang, and the House has passed a bill aimed at further curtailing North Korea’s access to the international financial system.

Meanwhile, American, Japanese and South Korean nuclear negotiators met in Seoul on Wednesday to talk about a coordinated response to the test.

[A North Korean H-bomb? Not likely, experts say.]

1 of 50 Full Screen Autoplay Close Skip Ad × What life looks like inside North Korea View Photos Scenes from inside the hermit kingdom. Caption Scenes from the hermit kingdom. April 14, 2016 A girl dances ballet at the Mangyongdae Children’s Palace in the Pyongyang suburbs. The large facility, opened in 1989, has hundreds of rooms for various activities, including mathematics, chemistry, computer science, sports, music and dance practice. Franck Robichon/European Pressphoto Agency Buy Photo Wait 1 second to continue.

North Korea carried out its fourth nuclear test on Jan. 6, claiming that it detonated a hydrogen bomb — which is enormously more powerful than the three atomic devices it previously tested. But seismic readings suggested that the bomb had a yield similar to what was seen in the earlier tests, leading experts to say that North Korea might have set off an atomic device that contained hydrogen isotopes and then claimed that it was a more powerful weapon.

Either way, the test has reignited tensions on the Korean Peninsula.

South Korea resumed broadcasting messages critical of Kim from speakers lined up along the demilitarized zone separating the two Koreas, and it sharply curtailed access to a jointly run industrial park on the northern side of the border. In response, North Korea started broadcasting its own messages critical of Park across the DMZ, although military officials said the speakers were too weak for the messages to be clearly heard, according to local reports.

North Korean propaganda pamphlets also were found in northern parts of Seoul and towns close to the DMZ, apparently carried across by big plastic balloons — mirroring a practice of South Korean activists who send anti-Kim leaflets northward.

“Stop the psychological warfare broadcasts that light the fuse of war,” one of the brochures said, according to Yonhap News Agency. “Knock out the gang of Park Geun-hye who aggravated North-South relations by resuming anti-North psychological warfare broadcasts,” another said.

Separately, South Korea’s military fired warning shots at a North Korean drone that briefly entered Southern airspace in the DMZ, sending the vehicle back into the North.

Yoonjung Seo contributed to this report.

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What do we know about Kim Jong Un? Very little. That makes this guy an expert.