President Trump on Friday called North Korea's dictator a "madman" and said that he will be "tested like never before."

Mr. Trump issued the threat on Twitter after the regime's leader, Kim Jong Un, responded to the president's speech before the United Nations General Assembly in which he said the U.S. could "totally destroy North Korea."

Kim Jong Un of North Korea, who is obviously a madman who doesn't mind starving or killing his people, will be tested like never before! — Donald J. Trump (@realDonaldTrump) September 22, 2017

On the sidelines of a U.N. gathering Thursday, North Korean Foreign Minister Ri Yong-ho said that Pyongyang may consider testing a hydrogen bomb over the Pacific Ocean in response to the U.S. expanding sanctions against the regime.

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Kim called Mr. Trump "deranged" Friday and said that he will "pay dearly" for his threats.

"I will make the man holding the prerogative of the supreme command in the U.S. pay dearly for his speech calling for totally destroying" the North, said the statement carried by the country's official Korean Central News Agency Friday morning.

The Trump administration announced a new executive order Thursday that the president said "significantly expands" U.S. authority to target companies and financial institutions that facilitate trade with North Korea.