The 2012 Seoul Nuclear Security Summit was supposed to be an opportunity for President Barack Obama and other leaders to find ways to keep nuclear material away from terrorists. So far, North Korea has upstaged that agenda.

And that may be just what Pyongyang intended.

Several of the heads of state meeting in Seoul have criticized the North’s surprise announcement 10 days ago that it plans to blast a satellite into space next month aboard a long-range rocket ― a launch that Obama’s government views as cover for nuclear missile development.

Obama urged North Korean leaders to abandon their rocket plan or risk jeopardizing their country’s future and thwarting a recent U.S. pledge of food aid in return for nuclear and missile test moratoriums ― considered a breakthrough after years of deadlock. South Korean President Lee Myung-bak’s government warned it might shoot down parts of the rocket if it violates South Korean air space.

Obama and Lee also pressed North Korean ally China to use its influence to prevent a launch. Meanwhile, a Chinese government-backed disarmament expert said allowing the launch to dominate discussions at the summit may be exactly what North Korea wants.

“I think North Korea did this to overshadow our talks about nuclear security,’’ said China Arms Control and Disarmament Association head Li Hong. “We shouldn’t fall for their trick.’’

Impoverished North Korea has a history of angling for food, oil and other concessions in exchange for disarmament pledges in on-again, off-again talks, and it periodically launches aggressive, attention-grabbing moves to ensure those negotiations stay high on the international agenda.

Why North Korea made its rocket announcement so soon after settling a nuclear freeze-for-aid deal last month with the United States has mystified some observers, because it endangers a pending aid shipment.

However, Pyongyang previously has upped the ante by creating crises during diplomatic talks on the nuclear standoff, including in 2009 when it launched a long-range, multistage rocket seen as a defying a U.N. ban. When the U.N. Security Council condemned that launch, Pyongyang responded by abandoning six-nation nuclear disarmament talks and, weeks later, carrying out a nuclear test, its second.

The following year saw violence blamed on North Korea that claimed the lives of 50 South Koreans and fears that the Koreas were near war. But Pyongyang then began a charm offensive, pushing for a resumption of the disarmament talks, and the U.S.-North Korea deal settled on Feb. 29 was seen as a breakthrough and a step toward resumption of those broader nuclear negotiations.

“If they raise hopes, then dash hopes, then come back again, they think they might get a better deal,’’ said Ralph Cossa, president of Pacific Forum CSIS, a Hawaii-based think tank. “The better the crisis, the better the deal.’’

Pyongyang also has been blamed for provocations ahead of previous major international events hosted by the South. The year before the 1988 Seoul Olympics, a bombing blamed on two North Korean agents killed 115 people aboard a South Korean airline. North Korea has never acknowledged responsibility.

The drama over North Korea’s latest plan for a satellite launch has also robbed attention from the summit’s moves to lock down the world’s supply of nuclear material by 2014. Participants were to release a communique about those efforts Tuesday.

It also takes the spotlight away from diplomacy meant to halt Iran’s suspected nuclear weapons program, though Obama stressed that he would press the issue of Iran in one-on-one talks with the leaders of Russia and China.

“Iran’s leaders must understand that there is no escaping the choice before it. Iran must act with the seriousness and sense of urgency that this moment demands,’’ Obama said.

North Korea has said it would launch its rocket around the April 15 celebration of the birthday of North Korean founder Kim Il Sung ― and that timing is probably not linked to this week’s nuclear summit, said Koh Yu-hwan, a North Korea professor at Seoul’s Dongguk University. However, the North may have timed its March 16 launch announcement with the global meeting in mind, he said.

“North Korea can demonstrate to the world how volatile and tense the situation on the Korean peninsula is’’ with the launch, he said. “That would help it achieve its interests in future negotiations.’’

North Korea moved its rocket into position just before the summit opened, South Korean officials said Sunday.

Yoo Ho-yeol, a professor at Korea University in the South, said Pyongyang has decided to launch a satellite because it believes it will help solidify new leader Kim Jong Un’s power at a time when it has vowed to build a thriving nation.

“North Korea doesn’t have many things to show off,’’ he said.

China, as North Korea’s biggest source of diplomatic support and economic assistance, faces pressure to get the North to halt its rocket plans. However, China maintains its leverage is limited by Pyongyang’s unpredictable nature and Beijing’s overriding concern for stability along its northeastern border.

Chinese President Hu Jintao met Monday with the South Korean president and later with Obama.

Ben Rhodes, Obama’s deputy national security adviser, said Hu indicated China was taking the launch seriously and letting its concerns be known to Pyongyang.

But, he added, “China has expressed those concerns before, and North Korea has continued on with its behavior.’’

“China needs to look at whether it needs to be doing more,’’ he said.

China will continue to express its concerns to North Korea ― and may send a high-level official to Pyongyang to press its case ― but won’t cut off aid for fear of destabilizing the new government, Peking University international relations expert Zhu Feng. (AP)