UNITED NATIONS, United States — The United States on Thursday sharply ramped up sanctions aimed at curtailing North Korea’s nuclear weapons drive, targeting the regime’s trading partners with a sweeping ban on business.

President Donald Trump unveiled the new measures as he met with the leaders of allies Japan and South Korea, even as key players China and Russia voiced unease with his more aggressive approach.

Two days after threatening in his first address to the UN General Assembly to "totally destroy North Korea", Trump signed an executive order that would ban firms from operating in the United States if they deal with North Korea.

"Foreign financial institutions are now on notice that going forward they can choose to do business with the United States or with North Korea, but not both," Treasury Secretary Steven Mnuchin said.

The United States already punishes foreign firms tied to North Korea’s military programmes but the latest action sharply expands the range, targeting businesses involved in everything from technology to fishing.

Financial companies may feel the biggest impact. Trump’s order also bans any aircraft or ship that has travelled to North Korea from landing in the United States.

The European Union readied its own sanctions. The 28-country bloc agreed to a ban on investments in North Korea and EU exports of oil to the regime, diplomatic sources said in Brussels.

North Korea in recent weeks detonated its sixth nuclear bomb and has test-fired intercontinental missiles -- saying it needs to defend itself against hostility from the United States and its allies.

The US administration has refused to offer North Korea incentives to open negotiations and has ramped up threats of military action to force leader Kim Jong-Un -- to change course.

But meeting with Japanese Prime Minister Shinzo Abe and South Korean President Moon Jae-in, Trump said "Why not?" when asked whether there could be a dialogue with North Korea.

Chinese Foreign Minister Wang Yi told the General Assembly there was still room for talks -- the polar opposite of remarks a day earlier by Japan’s Abe who said that past dialogue had achieved nothing.

"There is still hope for peace and we must not give up. Negotiation is the only way out and deserves every effort," said Wang, who also asked South Korea and Japan not to consider developing their own nuclear weapons.

Russian Foreign Minister Sergei Lavrov said that while his government condemns North Korea, "military hysteria is not just an impasse, it’s disaster". — AFP