The White House demanded Monday that the Chinese government stop the widespread theft of data from American computer networks and agree to “acceptable norms of behavior in cyberspace.”

The demand, made in a speech by President Obama’s national security adviser, Tom Donilon, was the first public confrontation with China over cyberespionage and came two days after its foreign minister, Yang Jiechi, rejected a growing body of evidence that his country’s military was involved in cyberattacks on American corporations and some government agencies.

The White House, Mr. Donilon said, is seeking three things from Beijing: public recognition of the urgency of the problem; a commitment to crack down on hackers in China; and an agreement to take part in a dialogue to establish global standards.

“Increasingly, U.S. businesses are speaking out about their serious concerns about sophisticated, targeted theft of confidential business information and proprietary technologies through cyberintrusions emanating from China on an unprecedented scale,” Mr. Donilon said in a wide-ranging address to the Asia Society in New York.

“The international community,” he added, “cannot tolerate such activity from any country.”

Until now, the White House has steered clear of mentioning China by name when discussing cybercrime, though Mr. Obama and other officials have raised it privately with Chinese counterparts. In his State of the Union address, he said, “We know foreign countries and companies swipe our corporate secrets.”

But as evidence has emerged suggesting the People’s Liberation Army is linked to hacking, the China connection has become harder for the administration not to confront head-on. The New York Times three weeks ago published evidence tying one of the most active of the Chinese groups to a neighborhood in Shanghai that is headquarters to a major cyberunit of the People’s Liberation Army. That account, based in large part on unclassified work done by Mandiant, a security firm, echoed the findings of intelligence agencies that have been tracking the Chinese attackers.

The United Nations Security Council approved a new regimen of sanctions on Thursday against North Korea for its underground nuclear test last month, imposing penalties on North Korean banking, travel and trade in a unanimous vote that reflected the country’s increased international isolation.

The resolution, which was drafted by the United States and China, was passed 15-0 in a speedy vote hours after North Korea threatened for the first time to launch a pre-emptive nuclear strike against the United States and South Korea.

“The strength, breadth and severity of these sanctions will raise the cost to North Korea of its illicit nuclear program,” the United States ambassador to the United Nations, Susan E. Rice, told reporters after the vote. “Taken together, these sanctions will bite and bite hard.”

Li Baodong, the ambassador from China, whose support for the new sanctions angered the North Korean government, told reporters the resolution was aimed at the long-term goal of denuclearizing the Korean Peninsula.

“This resolution is a very important step,” he told reporters. Mr. Li called passage of the resolution “a reflection of the view and determination of the international community.”