Beijing(CNN) U.S. Secretary of State John Kerry pressed China Wednesday to step up pressure on North Korea after its recent nuclear test and tone down its aggressive actions in the South China Sea.
Kerry met with Chinese President Xi Jinping and spent more than four hours with Chinese Foreign Minister Wang Yi and other senior officials.
North Korea and its intention to develop a thermonuclear weapon topped the agenda, said Kerry at a joint press conference with Wang.
"This is a threat to any nation in the world," he said. "So let me be clear, Kim Jong Un's actions are reckless and dangerous."
Wang said that North Korea had violated sanctions and agreed that the UN Security Council had to pass a new resolution but said any new resolution "must not provoke new tensions."
Washington wants Beijing to support more robust UN sanctions and to apply its own unilateral economic measures to curb North Korea's nuclear antics.
Pushing his point, Kerry said, there's room for the international community to get tougher with Pyongyang.
"With all due respect, more significant and impactful sanctions were put in place against Iran, which did not have a nuclear weapon than against North Korea, which does," he said.
Then challenging China further, Kerry said, "All nations, particularly those who seek a global leadership role, or have a global leadership role, have a responsibility to deal with this threat."
But Wang called China's response to North Korea's nuclear activity "clear cut" and "responsible."
"Our position will not be swayed by events or temporary mood of the moment," he said. "We have delivered on our obligation."
Tensions were visible between the two on the South China Sea, where a territorial dispute pits multiple countries against each other.
China has embarked on a massive land reclamation program, turning sandbars into islands equipped with airfields, ports and lighthouses, but Wang said China honored President Xi's commitment not to militarize the South China Sea -- made while he visited the White House in September.
He said that China had built civil installations and some necessary facilities for self defense.
"The international law has given all sovereign countries the right to self defense."
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A senior official traveling with Kerry said that he would test what China can do to cut off the regime's lifeline, as Pyongyang's largest benefactor and trading partner.
The two countries also have close political and military ties.
The U.S. has stressed to China that it should be very concerned that North Korea didn't warn China about the test ahead of time, thus illustrating the danger of North Korean leader Kim Jong Un's unpredictability
The senior official noted that in the past China had found ways to prevent North Korean provocations.
"The fact that despite China's friendly overtures to the DPRK, Kim Jong Un turned around and did the thing that he knew the Chinese most objected to—a nuclear test—certainly tells me that that message hasn't yet gotten through," the official said.
Kerry has said the nuclear test demonstrated that China's approach hadn't worked, and "we cannot continue business as usual."
Before his trip to Beijing, Kerry called North Korea's nuclear activity "one of the most serious issues on time planet today, which is a clearly reckless and dangerous evolving security threat."
In recent weeks U.S. officials made clear the U.S. is considering a new range of unilateral sanctions in response to North Korea's nuclear test, which could anger China.
This includes so-called "secondary sanctions" that target third-party countries. That would mainly affect China as North Korea's primary trade partner.
The U.S. could also beef up its defenses in the region.
Earlier this month South Korean President Park Geun-hye said she would consider allowing the U.S. to deploy an advanced missile-defense system—the Terminal High-Altitude Area Defense battery, or Thaad, something Washington has been pressing for and which China has opposed.
China has tried to shift the blame to the U.S.
Chinese officials have said they believe the U.S. could be exerting more influence on Kim if it wanted to, since Kim has long sought direct communication with Washington
Kerry comes to China after visiting Laos and Cambodia as part of an Obama administration effort to strengthen its partnership with the 10-member Association of South-east Asian Nations, known as ASEAN as a counterweights to China, which has been the dominant player in the region.
Next month Obama will host the 10 leaders of ASEAN in Sunnylands, California.
In addition to strengthening political and economic ties, the U.S. wants ASEAN to show more unity in response to China's growing assertiveness in the South China Sea, as Beijing steps up its building of made islands and airstrips in disputed maritime areas.