Beijing ? Hoping for a breakthrough, diplomats from six nations convened today in the Chinese capital for talks to resolve East Asia’s most urgent security concern — North Korea’s nuclear program and demands by the United States that it stand down immediately.

China, the host country, called for a “calm and patient attitude” for the meetings, put together after months of intense diplomacy. Envoys for the United States and North Korea shook hands, as did others, before they crisply got down to business.

South Korea, Russia and Japan are also participating.

“A warm welcome to you all,” Chinese Vice Foreign Minister Wang Yi told the diplomats before the meeting was closed to reporters. “I am very happy the six countries are all here.”

All six have a stake in the outcome — even beyond wanting to keep the isolated communist North from becoming a nuclear threat. South Korea wants to clear an obstruction from its policy of reconciliation with Pyongyang. Japan seeks progress on the issue of Japanese citizens kidnapped by the North during the Cold War.

China hopes to avoid being dragged into a conflict between its longtime ally, North Korea, and a vital trading partner, the United States. Pyongyang, faced with economic collapse, wants security guarantees and more food and humanitarian aid.

U.S. officials say they believe North Korea has one or two nuclear weapons, and experts believe it could produce five to six more in a few months. North Korea has walked away from a number of international agreements in recent months, including the Nuclear Nonproliferation Treaty.