The top U.S. military officer lashed out at China on Wednesday for failing to intervene diplomatically with North Korea, as he met with his South Korean counterpart to discuss possible armed responses to future provocations from Pyongyang. Adm. Mike Mullen, the chairman of the Joint Chiefs of Staff, sharply criticized Beijing for not condemning North Korea's artillery barrage against a South Korean island two weeks ago. Two marines and two civilians were killed in the attack, which has frayed diplomatic nerves in the region and brought both militaries to heightened states of alert. 'China has enormous influence over the North, and therefore they have a unique responsibility,' Mullen said after meeting with Gen. Han Min-koo, chairman of the South Korean Joint Chiefs. 'Now is the time for Beijing to step up to that responsibility and guide the North, and indeed the whole region, to a better future.' 'Even tacit approval of Pyongyang's brazenness,' he said, 'leaves all the neighbors in the region asking, 'What's next?'' Rather than disavowing the North's use of military force against civilians, China has instead criticized the response by Washington and Seoul -- a large set of military exercises in the Yellow Sea off China and North Korea, drills that were led by the U.S. carrier George Washington and its battle group. Han called the Nov. 23 attack on Yeonpyeong Island 'an intolerable act against humanity,' and said the United States and South Korea had agreed to hold further combined military exercises in the region. A joint statement by the two officers said the drills will be 'designed to effectively deter North Korean aggression and strengthen the joint capabilities to respond.' South Korea is holding a nationwide set of artillery drills this week. And the United States and Japan are currently staging their largest-ever war games, including, for the first time, South Korean observers. As part of its response to the Yeonpyeong episode, Beijing called for a restart of the so-called six-party talksaimed at dismantling North Korea's nuclear programs, which Pyongyang continues to pursue. North Korea recently unveiled a new uranium enrichment facility, which it said was operational, and a new light water reactor that is under construction. Washington, Seoul and Tokyo have rejected new talks. The South Korean and Japanese foreign ministers conferred with Secretary of State Hillary Rodham Clinton in Washington on Monday in what Mullen called 'a truly historic trilateral meeting.' 