UNITED NATIONS — The U.N. Security Council imposed punishing new sanctions on North Korea yesterday, toughening an arms embargo and authorizing ship searches on the high seas in an attempt to thwart the reclusive nation's nuclear and ballistic missile programs.

The unanimous support for the resolution reflected international disapproval for recent actions by North Korea, which defied the council by conducting a second nuclear test on May 25.

While the 15-nation council stopped short of authorizing military action to enforce these measures, its unanimous condemnation of North Korea was a diplomatic blow for the country's ailing leader Kim Jong Il, who has previously counted on China and Russia to derail efforts to impose sanctions.

North Korea vowed today to embark on a uranium enrichment program and "weaponize" all the plutonium in its possession as it rejected the sanctions.

North Korea also said it would not abandon its nuclear programs, saying it was an inevitable decision to defend itself from what it says is a hostile U.S. policy and its nuclear threat against the North.

The North will take "resolute military action" if the United States or its allies try to impose any "blockade" on it, the ministry said in a statement carried by the North's official Korean Central News Agency.

The ministry did not elaborate if the blockade refers to an attempt to stop its ships or impose sanctions.

Following yesterday's vote, China's U.N. ambassador, Yesui Zhang, said his government is "firmly opposed to the nuclear test," and that North Korean actions have "impaired" international efforts to halt the spread of nuclear weapons.

But he urged countries, apparently the United States, to "act prudently" in responding to North Korea, and he insisted that "under no circumstance should there be the use of force or threats of the use of force."

At the White House, Susan Rice, the U.S. ambassador to the United Nations, said the resolution's financial sanctions were "very robust" and had "teeth that will bite in North Korea."

For instance, she said, a provision banning all arms exports from North Korea would cut off a major source of foreign revenues that can be used for its nuclear programs.

Rice, who shepherded the resolution through two weeks of complex and sometimes difficult negotiations, said in Washington that the administration was "very pleased" with the council's "unprecedented" and "innovative" action.

She cautioned that North Korea could react to the resolution with "further provocation."

RESOLUTION DETAILS

Resolution 1874 seeks to deprive North Korea of financing and material for its weapons program and bans the communist country's lucrative arms exports, especially missiles. It does not ban normal trade, but does call on international financial institutions to halt grants, aid or loans to the North except for humanitarian, development and denuclearization programs.

China and Russia, the North's closest allies, supported the resolution, but stressed that it did not authorize the use of force against North Korea, a key demand by both countries. Diplomats said during the negotiations both countries pushed to ensure that the measures not hurt ordinary people in North Korea who face daily hardships.

Russia's U.N. ambassador, Vitaly Churkin, said his government had agreed to support the resolution only after the United States and its partners agreed to add language that would exclude the possibility of using force to compel by force compliance with the council demands. Churkin called the North's repeat nuclear test "a serious blow" to efforts to prevent the proliferation of nuclear weapons and said the resolution was "an appropriate response," targeted at the weapons programs.

China, meanwhile, insisted on an exemption for it and other suppliers from an arms embargo, allowing the sale of small arms and light weapons, including the signature AK-47 used by North Korea's giant military, according to council diplomats.

China's U.N. Ambassador Zhang Yesui said the nuclear test had affected regional peace and security. He strongly urged North Korea to promote the denuclearization of the Korean peninsula and return quickly to Beijing-hosted six-party talks aimed at dismantling its nuclear program.

The resolution demonstrates the international community's "firm opposition" to the atomic test, Zhang said, but it also "sends a positive signal" by showing the council's determination to resolve the issue "peacefully through dialogue and negotiations."

'SHINE A SPOTLIGHT'

The most controversial measure calls for the inspection of North Korean cargo on the high seas if there are "reasonable grounds" to believe it contains banned military equipment. But it is unclear how the council would compel a North Korean ship to allow such a search, since there is no provision to force compliance.

Under the terms of the resolution, a foreign vessel is permitted to board a ship suspected of transporting banned North Korean weapons or equipment only if the country where the vessel is registered agrees. If not, the resolution requires that country to direct the ship to an "appropriate" port to be searched. North Korea has warned that it would consider any attempts to board its ships to be an act of war, and that it would respond with force.

As a sign of China's uneasiness about ship searches, Zhang stressed that "countries have to act prudently, in strict accordance with domestic and international laws, and under the precondition of reasonable grounds and sufficient evidence."

Rice said the United States would "intensify our existing efforts to gather information that would allow us to determine if there is a suspect vessel on the high seas," she said.

If a vessel refuses inspection, Rice said, the United States will "shine a spotlight on it, to make it very difficult for that contraband to continue to be carried forward."

However, she said, while the U.S. will work to ensure that full implementation is achieved and "the bite is felt ... we're not going to get into a tit-for-tat reaction to every North Korean provocative act."