May 26 (Bloomberg) -- The Obama administration sought to rally China and Russia behind a response to North Korea’s nuclear test and missile launches yesterday and may seek options for direct talks with the reclusive regime.

The U.S. may also contemplate moves to stiffen international sanctions on North Korea’s Stalinist government as well as unilateral pressure on foreign entities aiding the regime.

President Barack Obama said the U.S. “will work with our friends and allies to stand up to this behavior.” Obama and Secretary of State Hillary Clinton spoke with their Japanese and South Korean counterparts and planned to consult with China and Russia. The United Nations Security Council agreed to pursue new measures against North Korea.

“The Obama administration needs to operate on several fronts simultaneously,” said Wendy Sherman, former President Bill Clinton’s North Korea adviser and now a principal at the Albright Group LLC consulting firm in Washington. “This is a tough day for the international community.”

The crisis complicates Obama’s fledgling efforts to engage North Korean leader Kim Jong Il’s regime and comes as the U.S. already is occupied with blunting Iran’s nuclear ambitions and the insurgency endangering Pakistan. The test and missile launches fulfilled North Korea’s threat to retaliate for the Security Council’s censure of an April 5 ballistic missile test.

Beyond Diplomacy

In the wake of the new tests, some argue that the U.S. and its allies must go beyond diplomacy to influence the North Koreans.

U.S. agencies, including the State and Treasury departments, must apply pressure on governments and companies that do business with North Korea, said Bruce Klingner, a senior research fellow at the Heritage Foundation policy group in Washington.

“There must be other entities, Chinese banks, etc., that must be complicit,” Klingner said.

Russia’s Defense Ministry said North Korea’s underground detonation occurred at 9:54 a.m. yesterday in the northern city of Kilchu and had a yield of between 10 and 20 kilotons. The U.S. characterized the yield as likely being a few kilotons and said its analysis was continuing, an administration official said.

Powerful Blast?

If verified, the test would dwarf North Korea’s first nuclear blast in October 2006, which had a yield of less than one kiloton, according to the office of the U.S. Director of National Intelligence. The atomic bomb dropped on Hiroshima, Japan, on Aug. 6, 1945, which killed some 140,000 people, had an estimated yield of 15 kilotons.

North Korea told the State Department of its intention to conduct a test less than an hour before a blast was detected, the administration official said. North Korea didn’t say when the test would occur.

Kim’s regime may be on a campaign to force other nations to recognize it as a nuclear power, said Victor Cha, a former Asia director at the White House National Security Council who now holds the Korea chair at the Center for Strategic and International Studies in Washington.

Response Options

Obama spoke this morning with South Korean President Lee Myung Bak and Japanese Prime Minister Taro Aso in separate phone calls. All three leaders agreed on the need for a Security Council resolution “with concrete measures to curtail North Korea’s nuclear and missile activities,” the White House said in a statement.

South Korea today said it will join the U.S.-led Proliferation Security Initiative that aims to stop shipments of weapons of mass destruction. North Korea had warned the South not to participate in the program.

For a response, the U.S. probably will need options beyond the UN and consultations with Russia, South Korea, Japan and China -- the four partners involved in talks to persuade North Korea to end its nuclear-arms program.

Direct contacts might occur through intermediaries, non- governmental groups or quasi-governmental channels, Sherman said.

Kim’s father, Kim Il Sung, responded positively to such an overture after North Korea withdrew from the nuclear Non- Proliferation Treaty in 1993. Former U.S. President Jimmy Carter traveled to the capital of Pyongyang on an unofficial mission that helped bring about an agreement in 1994.

North Korea rebuffed the Obama administration’s signals that special envoy Stephen Bosworth, appointed in February, was prepared to engage directly, beyond the six-nation negotiations that China had led.

Those talks foundered last year when North Korea refused to agree on ways to turn over soil samples from a nuclear site that would be used to verify claims about its program’s scope.

‘Want Attention’

“The North Koreans want the attention,” said Nicholas Szechenyi, a fellow at the Center for Strategic and International Studies. “If the objective is to get them to stop this behavior, then the Obama administration could conclude that the best thing would be to send a high-profile diplomat.”

China, which hosted the nuclear talks, may play a crucial role. China is North Korea’s biggest trading partner and counts on the country as a buffer to the U.S. military presence in the region and in relations with Japan and South Korea.

“We don’t have a North Korea problem, we have a China problem,” said Gordon Chang, author of “Nuclear Showdown: North Korea Takes on the World.” “Kim Jong Il couldn’t have detonated a weapon without Beijing’s support.”

The Chinese government said it “resolutely opposes” the nuclear test and demanded that North Korea return to disarmament negotiations.

North Korea’s actions raise concern that the country will share nuclear-weapons technology with other nations such as Iran, Klingner said. That compounds the need for tougher measures, he said.

The nuclear test may also reflect uncertainty within the regime.

In addition to North Korea’s economic struggles, U.S. and South Korean intelligence officials say they believe Kim suffered a stroke last August. He appointed his brother-in-law last month to a commission that controls the 1 million-person army.

To contact the reporter on this story: Viola Gienger in Washington at vgienger@bloomberg.net.

Last Updated: May 25, 2009 22:57 EDT