US President Donald Trump on Thursday announced new sanctions on North Korea with a focus on isolating individuals and businesses that facilitate the regime's nuclear weapons and ballistic missile programs.

In remarks broadcast live from New York, Trump said North Korea's weapons programs are a "grave threat" to world peace and security and called it "unacceptable" that some provide financial support to the "criminal, rogue" regime.

"Today I'm announcing a new executive order I just signed that significantly expands our authorities to target individuals, companies, financial institutions that finance and facilitate trade with North Korea," he said at the start of a trilateral luncheon meeting with South Korean President Moon Jae-in and Japanese Prime Minister Shinzo Abe.

"Our new executive order will cut off sources of revenue that fund North Korea's efforts to develop the deadliest weapons known to humankind," he said.

The order enhances the Treasury Department's authority to target any individual or entity that conducts "significant" trade in goods, services or technology with the North.

In particular, it allows sanctions to be placed on any foreign financial institution that "knowingly conducts or facilitates any significant transaction" on behalf of blacklisted individuals and entities or in connection with trade with North Korea.

The sanctions could be restrictions on relevant accounts in the US or their complete blockage, according to a White House statement.

The order also targets North Korea's shipping and trade networks by banning vessels and aircraft that have visited North Korea from visiting the US within 180 days. The ban also applies to vessels that have engaged in a ship-to-ship transfer with a vessel that has visited North Korea within 180 days.

"North Korea is dependent on its shipping networks to facilitate international trade," the White House said.

In addition, the order authorizes the Treasury Secretary to place sanctions on individuals involved in a range of industries in North Korea, including construction, energy, fishing and textiles; those involved in the ownership, control or operation of any port in the North; and others found to have had at least one "significant" trade transaction with North Korea in goods, services or technology.

"Foreign banks will face a clear choice: Do business with the United States or facilitate trade with the lawless regime in North Korea -- and they won't have so much trade," Trump said.

North Korea conducted its sixth and most powerful nuclear test on Sept. 3, drawing fresh UN Security Council sanctions, including caps on its imports of oil.

The Trump administration had pushed for a complete oil embargo but faced opposition from Russia and China, two of the five veto-wielding permanent members of the council.

The announcement sends a clear signal to China, North Korea's major ally and trading partner. Beijing is responsible for 90 percent of the North's external trade and has come under growing pressure to rein in its wayward neighbor.

Trump said China's central bank had just told the country's other banks to "immediately" stop doing business with North Korea, and thanked Chinese President Xi Jinping for that "very bold" and "unexpected" decision.

"This new order provides us with powerful new tools, but I want to be clear the order targets only one country -- and that country is North Korea," he said. "Many countries are working with us to increase economic and diplomatic pressure on North Korea. But I continue to call on all those responsible nations to enforce and implement UN sanctions and impose their own measures like the ones I am announcing today."

Both Moon and Abe welcomed the sanctions and offered their full support.

"I am very confident that such moves will contribute to complete denuclearization of (North Korea)," Moon said.

Treasury Secretary Steven Mnuchin echoed Trump's remarks in a press briefing later in the day.

"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," he said.

Troy Stangarone, senior director of the Korea Economic Institute of America, a think tank in Washington, said the sanctions' success will depend on the Treasury's determination to go after its targets and the extent of North Korea's transactions that are outside of US reach.

"In recent months, the WannaCry ransomware attack and North Korean cyberattacks on South Korean bitcoin exchanges demonstrate that Pyongyang is looking to move its transactions outside of the US financial system," he said. "Future efforts will need to find ways to crack down on cryptocurrencies to constrain North Korea's ability to conduct transactions."

Meanwhile, asked at the trilateral meeting if dialogue was still possible with North Korea, Trump quipped, "Why not?" (Yonhap)