US President Donald Trump has foreshadowed unilateral action against North Korea, describing the latest round of UN sanctions on Pyongyang as a “very small step”.

The UN Security Council on Tuesday unanimously voted to boost sanctions on North Korea, with its profitable textile exports now banned and fuel supplies capped, prompting a traditionally defiant threat of retaliation against the United States.

Monday’s decision, triggered by the North’s sixth and largest nuclear test this month, was the ninth such resolution unanimously adopted by the 15-member Security Council since 2006 over North Korea’s ballistic missile and nuclear programmes.

A tougher initial US draft was weakened to win the support of China, Pyongyang’s main ally and trading partner, and Russia, both of which hold veto power in the council.

On Wednesday morning (AEST), President Trump told reporters at the start of a meeting with Malaysian Prime Minister Najib Razak that he was pleased Malaysia no longer did business with North Korea, before adding that he had just discussed the UN vote with Secretary of State Rex Tillerson.

“We think it’s just another very small step, not a big deal. … I don’t know if it has any impact, but certainly it was nice to get 15-to-nothing vote.

“But those sanctions are nothing compared to what ultimately will have to happen,” he said without elaborating.

US Treasury Secretary Steven Mnuchin told a conference earlier that if China did not follow through on the new sanctions, “we will put additional sanctions on them and prevent them from accessing the US and international dollar system.”

Washington so far has mostly held off on new sanctions against Chinese banks and other companies doing business with North Korea.

North Korea’s ambassador, Han Tae Song, told the UN-sponsored Conference on Disarmament in Geneva on Tuesday the United States will soon face the “greatest pain” it has ever experienced.

The latest resolution also calls on countries to inspect vessels on the high seas, with the consent of the flag state, if they have reasonable grounds to believe the ships are carrying prohibited cargo to North Korea.

It also bans joint ventures with North Korean entities, except for nonprofit public utility infrastructure projects.

“The Washington regime fired up for political, economic, and military confrontation, (is) obsessed with the wild game of reversing the DPRK’s development of nuclear force which has already reached the completion phase,” Han said.

The Democratic People’s Republic of Korea (DPRK) is “ready to use a form of ultimate means”, he said without elaborating.

“The forthcoming measures by DPRK will make the US suffer the greatest pain it ever experienced in its history,” he said.

US disarmament ambassador Robert Wood took the floor to say the Security Council resolution “frankly sent a very clear and unambiguous message to the regime that the international community is tired, is no longer willing to put up provocative behaviour from this regime”.

“My hope is the regime will hear the message loud and clear and it will choose a different path,” Woods told the Geneva forum .

– With agencies