On Thursday, Reuters reported that China's central bank has told banks to stop doing business with North Korea amid us concerns that Beijing has not been tough enough about Pyongyang's repeated nuclear tests.
Speaking in New York, Mr Ri said his country would continue to escalate its weapons tests, after a claimed hydrogen bomb detonation near Pyongyang earlier this month.
"We use several methods to tell whether earthquakes are natural or man-made", said the official, who asked for anonymity.
China hoped that Japan talked and acted cautiously and played a constructive role on the nuclear issue, he said. "A new executive order will cut off sources of revenue that fund North Korea's efforts to develop the deadliest weapons known to human kind", he continued.
Trump has repeatedly said he will not hesitate to destroy North Korea if it attacks the U.S.
"Yes, it's unacceptable to silently watch North Korea's nuclear military adventures but it is also unacceptable to unleash war on the Korean Peninsula", he said.
Kim, in his statement, said Trump is "unfit to hold the prerogative of supreme command of a country".
North Korea's six previous nuclear tests have all been conducted underground.
Action is the best option in treating the dotard who, hard of hearing, is uttering only what he wants to say. "We have no idea about what actions could be taken as it will be ordered by leader Kim Jong Un".
North Korean leader Kim Jong Un sparked everyone's interest with his choice of words when he used a centuries-old insult to describe U.S. President Donald Trump.
It came in response to an unusual address the brazen dictator delivered a day earlier when he slammed Trump and vowed to "tame the mentally deranged USA dotard with fire".
North Korea's weakest nuclear test, its first one, conducted in 2006, generated a magnitude 4.3 quake.
Trump delivered a combative speech Tuesday at the UN General Assembly, where he mocked Kim as a "Rocket Man" on a "suicide mission".
The announcement came after Trump authorised the US Treasury to target firms doing business with North Korea.