Administration officials said the Chinese government had embraced an American plan to press the North to reconcile with the South after its deadly attacks on a South Korean island and a warship. The United States believes the Chinese also worked successfully to curb NorthKorea’s belligerent behavior.

China’s pressure, several senior officials said this week, might help explain why North Korea did not respond militarily to live-fire drills conducted this week by the South Korean military,when a previous drill drew an artillery barrage from the North that killed two South Korean civilians and two soldiers.

As evidence of the policy shift, officials pointed to recent remarks by China’s foreign minister, Yang Jiechi, in which he urged the North and South “to carry out dialogue and contact.” Previously, Beijing’sresponse had been to propose an emergency meeting of the six-party group that negotiates with North Korea over its nuclear program, a step the United States opposed as rewarding the North’s aggression.

China and the United States still have major differences on issues ranging from currency policy to climate change. And just last Sunday, skeptics pointed out, Beijing blocked a statement in the United Nations Security Council that would have explicitly condemned North Korea for the artillery attack.

Still, the agreement on how to deal with North Korea removes a substantial irritant in the Beijing-Washington relationship four weeks before President Hu Jintaoof China makes a state visit to Washington. It also creates a glimmer of hope, officials said, that the United States can resume a dialogue with North Korea, whose hostile behavior has raised tensions to the highest level since the Korean War.

“The silver lining of last weekend is that the Chinese, for the first time, were worried that things were spinning out of control,” said Victor Cha, a Korea expert at the Center for Strategic and International Studies who worked in the George W. Bush administration. “It moved the Chinese more in the direction we wanted them to move.”

The Obama administration claims some credit, too, noting that the change came on the heels of a visit to Beijing by American officials, led by Deputy Secretary of State James B. Steinberg.  A week before that, President Obama called Mr. Hu and bluntly urged him to put a tighter leash on the North Korean leader, Kim Jong-il.

China swiftly dispatched a senior diplomat to Pyongyang, the NorthKorean capital, and officials said he conveyed a strong message about “the unacceptability of attacks and killings of South Koreans,”  said asenior American official, who spoke on condition of anonymity in order to discuss sensitive diplomatic matters.

“The idea that there could be these one-off provocations without expectation of a military response, as the North had behaved in the past, the Chinese now understand that this is no longer the reality, no longer acceptable,” he said.

China’s push for a rapprochement between the North and South is even more significant, another official said, because it unifies the five parties that deal with Pyongyang: the United States, China, Russia, Japan and South Korea.  China’s reluctance to press North Korea was sending Pyongyang a mixed message, he said, especially since China is the North’s most influential ally.

Russia’s role has also been important, officials said. The Russian foreign minister, Sergey V. Lavrov, spoke out against the North Korean artillery shelling. And the comments by Mr. Yang, China’s foreign minister, about the need for North-South engagement came in a phone conversation with Mr. Lavrov that was released by the Chinese Foreign Ministry.

North Korea signaled that it was open to such an engagement in meetings with Gov. Bill Richardson of New Mexico, who made an unofficial visit to Pyongyang last weekend.  Mr. Richardson said the North was willing to ship spent fuel rods to South Korea — a move that could effectively end its production of plutonium, from which it has manufactured several nuclear bombs.

Administration officials played down Mr. Richardson’s trip, saying he was carrying no proposals from the United States. Shipping fuel rods to South Korea is not a new idea, one official noted, and the South Korean president, Lee Myung-bak, seems in no mood to accept it. North Korea has also done little to alleviate concerns about its recently disclosed uranium-enrichment facility, aside from its offer to Mr. Richardson to allow nuclear inspectors back into the country.

Nevertheless, Mr. Steinberg and Jeffrey A. Bader, a top White House adviser on Asia, are likely to visit Seoul soon to explore whether the temporary lull in North Korea’s aggression creates an opening for diplomacy.

If the North makes amends for the shelling last month of Yeonpyeong Island and the torpedoing of the South Korea warship, the Cheonan,which killed 46 sailors, officials said it could open the door to contacts between the United States and North Korea. But they were vague about what kind of gesture would be sufficient.

“The South needs to have satisfaction that their concerns over the seacts have been addressed,” an official said. “The North cannot go around the South; they cannot sidestep the South.”

By going ahead with military drills in the face of North Korea’s threats, analysts said Mr. Lee might have bought himself some room to negotiate. But, they added, outsiders should not read too much into the North’s decision to hold its fire; the government’s motives were, asever, cloaked in mystery.