China's earthquake administration said on Saturday it had detected a magnitude 3.4 earthquake in North Korea that was a "suspected explosion", but it was still unclear whether the nation had actually conducted a new nuclear test.
Amid a growing war of words between Pyongyang and Washington, Chinese officials said in a statement on its website that the quake, which occurred around 0830 GMT, was recorded a depth of zero kilometres.
Previous quakes from North Korea have indicated nuclear tests by the reclusive state, the most recent earlier this month. The quake was centred near North Korea's nuclear test site.
The president's comment came in response to Kim excoriating Trump for his speech at the United Nations earlier this week, which heightened fears of an armed conflict.