The Latest on the tensions on the Korean Peninsula (all times local):

1:40 p.m.

South Korea's Yonhap news agency says a second quake was detected near North Korea's nuclear test site.

The second quake measured 4.6.

South Korea's military said earlier Sunday that North Korea is believed to have conducted its sixth nuclear test after it picked up seismic waves measuring 5.6. The US Geological Survey called the first quake an explosion with a magnitude 6.3.

It came hours after North Korea claimed that its leader has inspected a hydrogen bomb meant for a new intercontinental ballistic missile.

___

1:30 p.m.

South Korea's military says North Korea is believed to have conducted its sixth nuclear test.

The Joint Chiefs of Staff in Seoul says in a statement South Korea's military has strengthened monitoring and readiness and is mulling a variety of possible responses that could be pushed together with its ally the US

The apparent test came just hours after North Korea claimed that its leader has inspected the loading of a hydrogen bomb into a new intercontinental ballistic missile.

___

1:05 p.m.

South Korea's Joint Chiefs of Staff says a magnitude 5.6 quake in North Korea was artificial and it's analyzing whether the North conducted a nuclear test.

It says it detected a seismic wave from 12:34 p.m. to 12:36 p.m. around Punggyeri, North Korea.

The quake came just hours after North Korea claimed that its leader has inspected the loading of a hydrogen bomb into a new intercontinental ballistic missile.

___

1 p.m.

South Korea's Yonhap News agency says a magnitude 5.6 quake has occurred in North Korea.

It isn't immediately clear whether North Korea has conducted its sixth nuclear test. North Korea conducted its fifth test last September.

The report came just hours after North Korea claimed that its leader has inspected the loading of a hydrogen bomb into a new intercontinental ballistic missile.

___

10:45 a.m.

The White House says President Donald Trump spoke with Japan's Prime Minister Shinzo Abe to discuss ``ongoing efforts to maximize pressure on North Korea.''

The statement did not say whether the conversation came before or after the North's latest claim that its leader has inspected the loading of a hydrogen bomb into a new intercontinental ballistic missile.

Sunday's statement by the state-run Korean Central News Agency will raise already high worries on the Korean Peninsula and in Washington that the North is closer to its goal of an arsenal of viable nuclear ICBMs that can reach the US mainland.

According to the White House statement, the two leaders reaffirmed the importance of close cooperation between the United States, Japan, and South Korea in the face of the growing threat from North Korea. Trump also noted that he looks forward to continued trilateral coordination on the margins of the United Nations General Assembly. (AP)