With its apparent successful launch of a satellite into orbit Wednesday, North Korea showed off an improving weapons program that Washington and its allies have struggled to curb, despite heavy international sanctions.

The incident illustrates what analysts described as the growing security risk posed by North Korea, as well as the increasing challenge facing Western countries as they search for ways to prevent such actions.

Pyongyang’s family-run government is already cut off economically from almost every country but China. United Nations sanctions have made it more difficult for the North to launder illicit money, import luxury goods and acquire some weapons materials. But U.N. sanctions and bans have not stifled North Korean missile launches, nuclear tests or weapons trades.

Instead, the North does as it pleases, relying on domestic and illegally imported technology, in part because it has little fear about further international condemnation, some security analysts said.

The surprise launch sets back the Obama administration’s goal of engaging North Korea and its new leader in hopes of moderating their behavior and eventually drawing the North back to international denuclearization talks.

North Korea’s leaders have said “they want to have talks, they want to get to normalization,” State Department spokeswoman Victoria Nuland said Wednesday. “And they continue to take actions that take them further from that.”

She would not comment on whether the United States sees any additional ways to apply pressure on North Korea but said the administration believes that China retains influence over its ally and should use it.

Although the Unha-3 rocket did not carry a warhead, it relied on technology similar to that of a long-range missile. The U.N. Security Council issued a statement Wednesday condemning the launch, calling it a “clear violation” of Security Council resolutions that ban tests of intercontinental ballistic missiles. But the 15-nation council, facing Chinese opposition to sanctions, stopped short of threatening any new penalties against Pyongyang. Instead, the council noted that it threatened in April to take action against North Korea if it launched further tests and vowed to “continue consultations on an appropriate response.”

North Korea says its satellite-launching program is about space research, not weapons technology, and is permissible under an international space treaty.

“The right to use outer space for peaceful purposes is universally recognized by international law,” North Korea’s state-run news agency quoted its Foreign Ministry spokesman as saying.

Some U.S. officials call Pyongyang their most vexing diplomatic challenge. Over the past 20 years, various U.S. governments have tried to pressure the North, engage with it, approach it one-on-one and deal with it in groups that include China, Russia, South Korea and Japan.

President Obama’s approach to the North is often described as “strategic patience” — essentially using sanctions while also pushing leader Kim Jong Eun to cease his bad behavior, with the promise of engagement if he does.

Critics of the Obama administration said Wednesday that North Korea’s launch should prompt the White House to rethink its strategy.

“The Obama administration’s approach continues to be unimaginative and moribund,” Rep. Edward R. Royce (R-Calif.), the incoming chairman of the House Committee on Foreign Affairs, said in a statement.

Sen. John F. Kerry (D-Mass.), chairman of the Senate Foreign Relations Committee, said in a statement that the launch would further isolate North Korea and that “the United States, our allies and our partners will take appropriate steps to safeguard our national security.”

Weapons development is North Korea’s pet project, used to show off the strength of a country that struggles with food shortages, bans dissent and sends political opponents to prison camps. A South Korean official told the Yonhap news agency that the North had spent between $2.8 billion and $3.2 billion on its weapons program over the past 14 years, dating to its first failed long-range missile test.

But until Wednesday, the spending had delivered little clear payoff. Four previous long-range rocket and missile tests — three for the purported purpose of placing a satellite into orbit — all failed. One broke up 40 seconds after launch. Two traveled more than a thousand miles. The previous rocket, in April, exploded about 90 seconds after takeoff and dropped into the sea.

On Wednesday the three-stage rocket sailed southward, slicing between China and South Korea, then soaring over Okinawa. One booster stage, as planned, dropped in the Yellow Sea. Another dropped in the East China Sea, near the Philippines. The third and final stage carried the payload — a satellite named Kwangmyongsong-3 — into orbit, where it was detected by international tracking systems.

North Korea’s state-run media — which have described several previous failures as successes — said the satellite entered orbit nine minutes and 27 seconds after liftoff.

Security experts cautioned that North Korea must still overcome several hurdles before it can directly threaten the United States with an intercontinental ballistic missile. It must miniaturize a nuclear weapon so it is small enough to mount on the rocket and hone technology that will allow the device to reenter the atmosphere from space.

In addition, “what [the latest test] doesn’t show is that they have any idea what the reliability is,” said David Wright, a missile and global security expert at the Union of Concerned Scientists.

A Chinese Foreign Ministry spokesman said Wednesday that Beijing “regrets” that North Korea carried out the launch. He also called for the “relevant parties to keep calm and work together to maintain peace and stability on the Korean Peninsula.”

At a July meeting in Singapore between several U.S. experts and North Korean officials, first publicized by Foreign Policy, the North Koreans said they still wanted engagement with Washington. But they also felt they had leverage.

“They had a little bounce in their step,” said Joel Wit, a former U.S. nuclear negotiator who took part in the meetings. “They feel like they were making progress [with their weapons program] and had weathered whatever sanctions we can throw at them. I think the North Koreans, having gone through four years of strategic patience, are pretty fat and happy.”

Yoonjung Seo in Seoul, Liu Liu in Beijing, Anne Gearan in Washington and Colum Lynch at the United Nations contributed to this report.