"North Korea, NoKo, you are not allowed to insult our leader like that", said Colbert, feigning outrage. He said the action "was a somewhat unexpected move and we appreciate it".
Kim Jong Un calls Trump a mentally deranged USA dotard.
North Korean Foreign Minister Ri Yong Ho said Thursday in NY that in "his opinion", leader Kim Jong Un was prepared to conduct the "most powerful test of a hydrogen bomb in the Pacific Ocean".
He called Mr Trump "mentally deranged" and said the US President's comments were "the most ferocious declaration of war in history".
"Little rocket man. We're going to do it".
USA experts assess that North Korea is six to eight months from building a nuclear warhead capable of surviving the intense heat and vibrations of an intercontinental ballistic missile capable of reaching the continental United States.
Trump's tweet comes after Kim Jong Un blasted the US President as "mentally deranged" and vowed to make him pay dearly for threatening to destroy his country.
It imposes a 180-day ban on vessels and aircraft that have visited North Korea from visiting the United States.
On Thursday, Trump announced new USA sanctions against other countries, foreign businesses and individuals that do business with North Korea, a move likely to chiefly affect China, Pyongyang's largest trading partner.
And earlier in September, Trump described North Korea as "a rogue nation" and "embarrassment to China".
Vipin Narang, a nuclear strategy expert at MIT, said that such a test could pose a danger to shipping and aircraft, even if the North declared a keep-out zone.
The tension on the Korean peninsula escalated following the statement of Ri Yong-ho, the foreign minister of Pyongyang.
The United Nations Security Council had also condemned the recent launch of another ballistic missile by the Democratic People's Republic of Korea (DPRK) and called on the country's leadership to halt such activities and explore resumption of honest dialogue on de-nuclearisation.
Raising concern over the North Korean missile-tests, Chinese Foreign Minister Wang Yi had said that negotiations is the only way to find out the solution and urged the ruling Democratic People's Republic of the Korean Government to not go further in "dangerous direction".
He called for a political process, which he said was a key part of the United Nations Security Council process.