A small earthquake that hit North Korea Saturday near the country's nuclear test site was likely a natural tremor and not a nuclear explosion, neighboring countries said.
A South Korea Meteorological Agency spokesman said that acoustic waves from a man-made explosion should have been detected but were not.
China's Earthquake Administration said the quake was not a nuclear blast after saying earlier the 3.4 magnitude quake detected at 0829 GMT was a "suspected explosion."
The U.S. Geological Survey, however, said it could not confirm whether Saturday's seismic activity was man-made or natural.
After Saturday's tremors, U.S. Air Force fighter jets escorted bombers in international airspace over waters east of North Korea.
The Pentagon said the patrols are designed to display the numerous military options Trump has at his disposal in response to the threat presented by North Korea's nuclear program.
Saturday's seismic activity occurred only hours before North Korean Foreign Minister Ri Yong Ho addressed the United Nations General Assembly in New York.
Ri had warned Thursday that North Korea may consider an even larger hydrogen bomb test in the Pacific region.
Ri's warning further escalated the tensions that have grown around the Korean Peninsula since Pyongyang conducted its sixth nuclear test, prompting the U.N. to impose new sanctions on the country.