Seoul, South Korea (CNN) -- The head of the U.S. Joint Chiefs of Staff on Wednesday joined a chorus of American officials calling for China to take a leading role in defusing tension on the Korean peninsula, specifically using its influence with North Korea.
"The Chinese have enormous influence over the North, influence that no other nation on Earth enjoys," Adm. Mike Mullen, the chairman of the U.S. Joint Chiefs of Staff, said at a news conference in Seoul, South Korea. "And yet, despite a shared interest in reducing tensions, they appear unwilling to use it."
Mullen is in Seoul to meet with defense leaders and demonstrate the strength of the U.S.-South Korea alliance.
Tensions on the Korean peninsula escalated following North Korea's shelling of South Korea's Yeonpyeong Island last month, as well as the March sinking of a South Korean warship -- allegedly by a North Korean torpedo -- and recent revelations that it is enriching uranium for nuclear weapons.
"Even tacit approval of Pyongyang's brazenness leaves all their neighbors asking, '... What will be next?'" Mullen said in his challenge.
"China has unique influence. Therefore, they bear unique responsibility," he said. "Now is the time for Beijing to step up to that responsibility and help guide the North, and indeed, the entire region, towards a better future."
Mullen's comments came a day after U.S. Deputy Secretary of State James Steinberg made a similar plea to China, regarding North Korea, during a speech to the Center for American Progress, a Washington think tank. Steinberg is leading a delegation to Asia next week on the heels of the visit by Mullen.
And on Monday, Secretary of State Hillary Clinton hosted the foreign ministers of South Korea and Japan at the State Department, where the trio pledged support for South Korea, and also urged China to take on a larger role in constraining Pyongyang.
"The tensions that we see and the dangers that we see come from the fact that (there) does not seem to be effective restraints on North Korea ... in these provocations," Steinberg said in his speech. "We need to make clear the dangers (that) come from this provocative behavior. And rather than stepping back and tolerating it, we need to make clear that there are consequences for it."
President Barack Obama called Chinese President Hu Jintao on Sunday -- Monday in China -- and told him that North Korea needs to "halt its provocative behavior," according to the White House.
The state-run Chinese news agency Xinhua reported that Hu called for a "calm and rational response from all sides to prevent the deterioration of the fragile security situation" on the Korean peninsula.
North Korean officials have been pushing for the resumption of six-party talks including China and Russia. China has also called for "emergency" talks among all the six countries to address the tensions on the Korean peninsula.
But the United States has thus far refused, looking first for proof that North Korea is serious about not stoking military tensions and serious about stifling development of its nuclear program.
But Mullen said the United States doesn't believe talks would be productive without some evidence that North Korea is ready to end its behavior and take part in a serious dialogue.
"We first need an appropriate basis for the resumption of talks," he said. "There is none, so long as North Korea persists in its illegal, ill-advised and dangerous behavior. I do not believe we should continue to reward that behavior with bargaining or new incentives."
CNN's Elise Labott and Barbara Starr contributed to this report.