North Korea claimed to have detonated a new hydrogen bomb Sunday, confirming suspicions of the reclusive state's sixth-ever nuclear test after outside monitors noted a large artificial earthquake.

Axar.az reports citing Anadolu agency that, Seoul's Korea Meteorological Administration observed a 5.7-magnitude tremor around the North’s Punggye-ri test site at 12.29 p.m. local time, while the U.S. Geological Survey recorded it as a 6.3-magnitude -- either way, significantly stronger than the 5.04-magnitude quake triggered by the reclusive state's fifth nuclear test a year ago.

South Korea's Joint Chiefs of Staff had announced earlier Sunday that North Korea was "presumed" to have carried out its sixth nuclear test.

Pyongyang's official KCNA news agency later announced the "perfect" test involved a hydrogen bomb that could be mounted on a North Korean intercontinental ballistic missile or ICBM.

"The H-bomb test was carried out to examine and confirm the accuracy and credibility of the power control technology, and internal structural design newly introduced into manufacturing the H-bomb to be placed as the payload of the ICBM," the agency reported.

The same news outlet published images earlier Sunday showing leader Kim Jong-un inspecting a new H-bomb warhead.

U.S. President Donald Trump said shortly after the test was confirmed that "talk of appeasement" will not work, singling out Seoul's efforts to broach the crisis diplomatically.

"They only understand one thing!" he said on Twitter, referring to the North.

"North Korea is a rogue nation which has become a great threat and embarrassment to China, which is trying to help but with little success," he added.

In response to a reporter's shouted question about whether he is planning an attack on the North, Trump responded: "We'll see".

After meeting with Trump and a select group of senior officials at the White House, U.S. Defense Secretary James Mattis stressed an "ironclad” U.S. commitment to its allies.

"Any threat to the United States or its territories, including Guam, or our allies will be met with a massive military response, a response both effective and overwhelming," Mattis told reporters.

Earlier Sunday, Treasury Secretary Steve Mnuchin said Washington is prepping a new round of economic sanctions that would end “all trade and other business" with the North.

The North has been openly developing its weapons technology amid regular threats to strike the U.S. mainland, despite being barred from conducting nuclear and ballistic missile tests.

Pyongyang is likely to incur international punishment, although the UN Security Council only recently strengthened sanctions following two North Korean ICBM launches in July.

Seoul and Washington’s security chiefs, Chung Eui-yong and H.R. McMaster, respectively, held 20-minute telephone talks soon after the test, according to South Korean news agency Yonhap.

"President Moon Jae-in said the country will never allow North Korea to continue advancing its nuclear and missile technologies," Chung said at an afternoon press briefing after an emergency meeting of South Korea's National Security Council, which apparently agreed to push for stronger punitive measures against Pyongyang and to consider deploying powerful American strategic weapons on the Korean Peninsula.

There are already approximately 30,000 U.S. military personnel stationed in the South, but more potent hardware -- such as B-1B bombers -- currently has to be flown in from American bases on Guam.