LOS ANGELES, CA (Catholic Online) - State-run Korean Central News Agency claimed that the test was conducted in a safe manner and is aimed at coping with "outrageous" US hostility that "violently" undermines the North's peaceful, sovereign rights to launch satellites.

"The high-level nuclear test, unlike in the past, had more explosive power and involved a miniaturized and lighter atomic bomb and was staged safely and perfectly," the agency said.

The test came to light after seismic activity measured 4.9 magnitude was registered by the U.S. Geological Survey.

United Nations Secretary-General Ban Ki-moon condemned the test, describing it as "deplorable."

"The secretary-general condemns the underground nuclear weapon test conducted by [North Korea] today," Ban's spokesman Martin Nesirky said in a statement. "It is a clear and grave violation of the relevant Security Council resolutions."

Further criticism came from U.S. President Barack Obama described the test as a "highly provocative act" that "undermines regional stability." Other countries, including the isolated North's closest ally, China, condemned the test. North Korea's closest geographical rival Japan said it was "extremely regrettable." Russia called it a violation of Pyongyang's international obligations.

South Korean defense ministry spokesman Kim Min-seok said the test had an explosive yield of at least six or seven kilotons, significantly more than North Korea's two previous tests in 2006 and 2009.

In response, the South Korean defense ministry raised its military alert level, saying the country was on alert for additional nuclear activity or a missile launch.

The U.N. Security Council will meet for emergency consultations. South Korea is the current president of the 15-country Security Council and had been calling for strong action against its neighbor in the event of a nuclear test.

China expressed "firm opposition" to the test, saying its ally had gone ahead with the blast "despite widespread opposition from the international community."

"We strongly urge the DPRK [North Korea] to honor its commitment to denuclearization, and not to take any actions which might worsen the situation," the foreign ministry said in a statement.

China had made a special effort to try to head off the bomb test -- but China's relationship with North Korea might change under the new Chinese leadership due to take over in March.

"It may no longer tolerate what has become a bigger and bigger thorn in its side," an Al Jazeera correspondent said.

"The new president, Xi Jinping, has made it very clear he intends to make relationships between China and the U.S. better. He wants to redefine them and possibly find a way that they can move forward, working with each other."

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