National geological agencies could not confirm on Saturday what caused an quake in North Korea at the same site where it had conducted a nuclear test.
For reference, the US agency recorded a 6.3 magnitude quake after North Korea's hydrogen bomb test on September 3, its sixth of a nuclear weapon.
Separate geological agencies had detected two artificial tremors near North Korea's previous test site before the country touted its "perfect success" in a special announcement later that day.
As of Saturday afternoon, however, the Chinese had not modified their assessment, and the United States Geological Survey said in a statement, "We can not conclusively confirm at this time the nature (natural or human-made) of the event".
China's seismic service CENC on Saturday detected a zero-depth, 3.4-magnitude natural disaster in North Korea, calling it a "suspected explosion".
Tensions have continued to rise since North Korea carried out its sixth nuclear test, prompting a new round of United Nations sanctions. Incidentally, today's quake was centred near North Korea's nuclear test site.
The latest test was followed by a second magnitude 4.1 quake that experts said could have been caused by landslides or a tunnel collapsing after the explosion.
Earlier this month, a 6.3 natural disaster shook North Korea before the country's state media claimed that it had carried out a successful hydrogen bomb test. It measured the quake at 3.5 magnitudes on the Richter scale.
The quake came just hours after North Korean Foreign Minister Ri Yong Ho suggested on Friday that the country could conduct an atmospheric hydrogen bomb test.More news: Egypt's Sisi Meets Netanyahu in NY
China, the closest ally of North Korea, accounts for about 90 per cent of Pyongyang's foreign trade.
Tensions have been high between North Korea and the United States since July, when the North test-fired two ICBMs purportedly capable of targeting the mainland US.
If some days ago u.s. leader threatened to "rocket man" to "completely destroy" ir country, yesterday Kim responded with a virulent diatribe towards "old chocho american" and threatened to "exercise hardest countermeasure of History", which could be launch of a hydrogen bomb over Pacific.
"At present, management of North Korea-related business has become an issue of national-level politics and national security", according to the document seen by the sources.
On Friday, China announced it would limit its exports of refined petroleum products to North Korea beginning in October 1 to comply with United Nations resolutions. It will also ban imports of textiles from North Korea.
Tillerson spoke Thursday at a ministerial meeting of the U.N. Security Council called by the United States on "the acute threat" posed by the proliferation of nuclear, chemical and biological weapons.
One project that has been discussed in the past involves building gas pipelines from Russian Federation to South Korea through North Korea.