Samantha Power, U.S. Ambassador to the U.N., where the Security Council adopted sweeping new sanctions on North Korea. (AP Photo/Julie Jacobson)

The U.N. Security Council unanimously adopted harsh sanctions Wednesday against North Korea, imposing some of the strongest measures ever used to pressure Pyongyang to abandon its nuclear weapons program.

The new sanctions come two months after North Korea tested what it claimed was a hydrogen bomb and a month after it conducted what was widely described as a banned missile test under the guise of launching a satellite into space. But U.S. officials began drafting the measures three years ago, soon after North Korea conducted a previous nuclear test, in order to move swiftly the next time it happened. Negotiations to win China’s support began two days after North Korea’s January nuclear test, its fourth in a decade.

The resolution is far more sweeping than existing sanctions requiring a link to proliferation activities. That precondition has been removed, in effect erasing the presumption of innocence.

[Punishing North Korea: A rundown on current sanctions]

It mandates cargo inspections for all goods going in and out of North Korea by land, sea or air, chokes off supplies of most aviation fuel for its armed forces, and bans the sale of all small arms and conventional weapons to Pyongyang. It also prohibits transactions that raise hard cash for North Korea through sales of its natural resources.

The resolution doubles the blacklist of people and institutions already sanctioned and requires countries to expel North Korean diplomats involved in any sanctioned activities.

One provision was designed to prevent Pyongyang from sending taekwondo instructors to train foreign police forces. Another bars North Koreans from specialized training at any school or research center in the world if the learning can advance Pyongyang’s nuclear and ballistic missile programs.

President Obama welcomed the sanctions as a firm and appropriate response to North Korea’s attempts to develop weapons of mass destruction.

“Today, the international community, speaking with one voice, has sent Pyongyang a simple message: North Korea must abandon these dangerous programs and choose a better path for its people,” he said.

As soon as the sanctions were released, the Treasury Department and the State Department updated their blacklists of people and entities tied to the Democratic People’s Republic of Korea, the official name for North Korea, and its proliferation programs. The designation freezes their U.S. assets and bars Americans from doing business with them.

The U.N. sanctions, which target the country’s elites and avoid “adverse humanitarian consequences” for civilians, aim to accomplish what worked with less onerous sanctions on Iran by pushing the impoverished nation to quit pumping money into its nuclear program.

[After nuclear test, Park has epiphanies on North Korea — and China]

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“The chronic suffering of the people of North Korea is the direct result of the choices made by the DPRK government, a government that has consistently prioritized its nuclear weapons and ballistic missile programs over providing for the most basic needs of its own people,” said Samantha Power, the U.S. ambassador to the United Nations.

“The North Korean government would rather grow its nuclear weapons program than grow its own children,” she added.

The resolution was presented by the United States with the support of China, a sharp reversal, given Beijing’s longtime support of its neighbor. Although the United States has long had an embargo on trade with North Korea, China has provided food and fuel and has been a key trading partner. In recent years, living conditions in North Korea have improved, thanks in large part to China.

In the past, China has been unwilling to tighten the screws on Pyongyang, in part out of concern for what an imploding, unstable North Korea might mean for China’s own border. But recently North Korea has continued testing new weapons and missiles, disregarding China’s warnings and personal envoys.

After North Korea on Jan. 6 detonated a new device — calling it a hydrogen bomb, although most experts say it was a smaller nuclear device — China’s ambassador to six-party talks, Wu Dawei, went to Pyongyang to urge restraint. Instead, North Korea announced while he was there that it would test a missile.

China’s about-face suggests it has started to realize that doing nothing would impose growing political costs internationally — the possibility of a greater U.S. presence in the region and weaker relations with South Korea, which Beijing has been cultivating.

“I expect there’s been a delayed recognition in China to the political price China was paying, with South Korea in particular, for its equivocation or outright silence about how to respond to North Korea and North Korea actions,” said Jonathan Pollack, a specialist on East Asian politics and security at the Brookings Institution.

[China, U.S. cite progress on N. Korea sanctions deal. But there’s no quick fix.]

During a visit to Washington last month, Chinese Foreign Minister Wang Yi hinted at the strains in policy toward North Korea.

“On the one hand, we’re saying to the international community . . . that the normal exchanges, especially those affecting the livelihoods of the North Korean people, should not be adversely affected,” he said at the Center for Strategic and International Studies. “On the other hand, in order to uphold the international nuclear nonproliferation regime for the sake of denuclearization, our exchanges will be affected to some extent.”

But some analysts question the depth of China’s commitment to the latest round of sanctions.

“The real question going forward is whether China will enforce the new measures,” said Victor Cha, a professor at Georgetown University. “My guess is that China will squeeze for a little bit, but not too hard, while the U.S. will want China to squeeze harder and for a longer period of time.”

Sung-Yoon Lee, a Korean studies professor at Tufts University, said the U.N. sanctions, even if violated in the future, will become increasingly meaningful if ordinary citizens in North Korea are adversely affected.

“The fact the U.N. is involved will lend greater legitimacy to the effort to sanction North Korea and enable others, like Japan and Europe, to shoulder some of the blame if there are negative repercussions from sanctions, so the blame doesn’t just fall on the shoulders of the United States,” he said.

Preparatory work on the sanctions began in early 2013, immediately after the Security Council passed a sanctions resolution in response to North Korea’s third nuclear test, according to a State Department official who spoke about the sensitive negotiations on the condition of anonymity. U.S. officials concluded that incrementally ratcheting up sanctions was insufficient and that more restrictive measures were needed, the official said.

As technical experts from many government agencies met to share ideas, a contingency draft of sanctions was repeatedly updated to be ready for a fourth nuclear test by North Korea.

[As U.S. pressure mounts, China talks up prospect of N. Korea sanctions that ‘bite’]

On Jan. 8, two days after North Korea announced the fourth test, diplomats from the U.S. mission to the United Nations presented a draft to the Chinese mission. There was little response during January as China studied the proposed sanctions, which dropped requirements to prove proliferation links, as China had insisted on previously.

China did not change its position during a Jan. 27 visit to Beijing by Secretary of State John F. Kerry or during a Feb. 5 phone call that Obama placed to Chinese President Xi Jinping.

But after the Feb. 7 missile test, the State Department official said, the Chinese came around to the U.S. point of view. Throughout much of February, U.S. and Chinese diplomats met several times a day to discuss provisions that had to be approved by Beijing, the official said.

“At 8 or 9 at night, diplomats at the U.S. mission would schlep to the Chinese mission,” the State Department official said. Then they would meet again the next day after Beijing had worked through the provisions overnight.

After a tentative agreement was reached early last week, U.S. officials had hoped for a quick adoption by the Security Council. But there were delays while Russia studied the sanctions to gauge their impact. Russia transports coal over a short stretch of railroad in North Korea to a port, and Moscow wanted reassurances it would not be banned, the official said.

In recent days, North Korea has boasted that more sanctions would not hurt. Now China, South Korea, Japan and the United States are awaiting its reaction. Early Thursday, hours after the sanctions were approved, the North fired short-range projectiles into the sea, South Korea’s Defense Ministry said.

“We’ve seen its reckless and unpredictable acts for years,” Power said. “We’ve seen threats directed at the continental United States and the Republic of Korea. We’ve seen cyberattacks on American companies costing hundreds of millions of dollars. We do not expect a change of behavior overnight.”

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