Obama: North Korea Nuclear Test Demands 'Serious Consequences'

— -- North Korea confirmed its fifth nuclear test explosion early Friday, its largest yet. The provocation brought instant condemnation from the country's neighbors and a call from President Obama for "serious consequences."

Pyongyang also said it has made strides that could bring it closer to mounting a warhead on one of its ballistic missiles and launching a long-distance nuclear strike.

"We successfully conducted a nuclear explosion test to determine the power of [the] nuclear warhead," a female anchor announced on North Korea's state television. "We will continue to strengthen our nuclear capabilities to protect our sovereignty. We have now standardized and minimized nuclear warheads ... We can now produce small nuclear warheads any time we desire."

South Korea's defense ministry said the yield of the blast is estimated to be 10 kilotons, the largest ever conducted by Pyongyang. Its first nuclear test in 2006 yielded less than one kiloton, and the country has been steadily increasing its atomic capacity ever since.

The United States Geological Survey registered a magnitude 5.3 explosion "near the location where North Korea has detonated nuclear explosions in the past."

"We are aware of seismic activity on the Korean Peninsula in the vicinity of a known North Korean nuclear test site," said National Security Council Spokesperson Ned Price. "We are monitoring and continuing to assess the situation in close coordination with our regional partners."

"Today’s nuclear test by the Democratic People's Republic of Korea, if confirmed, is its second this year and the fifth since 2006," said International Atomic Energy Agency Director General Yukiya Amano. "This is in clear violation of numerous UN Security Council resolutions and in complete disregard of the repeated demands of the international community. It is a deeply troubling and regrettable act."

North Korea previously conducted nuclear tests in 2006, 2009, 2013, and most recently in January 2016.

South Korean President Park Geun-hye called the explosion an act of "fanatic recklessness."

The White House said National Security Adviser Susan Rice briefed Obama on the incident.

"The president also consulted with President Park of the Republic of Korea and Prime Minister Abe of Japan in separate phone calls," White House press secretary Josh Earnest told ABC News. "The president reiterated the unbreakable U.S. commitment to the security of our allies in Asia and around the world. The president indicated he would continue to consult our allies and partners in the days ahead to ensure provocative actions from North Korea are met with serious consequences."

The U.S. State Department also told ABC News it was aware of the explosion.

"We are aware of seismic activity on the Korean Peninsula in the vicinity of a known North Korean nuclear test site," State Department spokesman John Kirby said. "We are monitoring and continuing to assess the situation in close coordination with our regional partners. The Secretary has been briefed on this incident."

China's foreign ministry condemned North Korea's nuclear test and said it will lodge a diplomatic protest with Pyongyang's ambassador in Beijing. The foreign ministry issued a statement saying it "resolutely opposes" the test and "intensely urges" Pyongyang to abide by its non-proliferation promises.

Japanese Prime Minister Shinzo Abe said the test explosion "could not be tolerated."

The Associated Press contributed to this report.