NEW YORK 鈥 U.S. President Donald Trump has added economic action to his fiery military threats against North Korea, and renewed his rhetorical offensive against Kim Jong Un on Friday, calling the reclusive leader 鈥渙bviously a madman.鈥

Trump鈥檚 move to punish foreign companies that deal with the North was the latest salvo in a U.S.-led campaign to isolate and impoverish Kim鈥檚 government until his country halts its missile and nuclear tests. Trump announced the measures Thursday as he met leaders from South Korea and Japan, the nations most immediately imperiled by North Korea鈥檚 threats of a military strike.

鈥淣orth Korea鈥檚 nuclear weapons and missile development is a grave threat to peace and security in our world and it is unacceptable that others financially support this criminal, rogue regime,鈥 Trump said as he joined Japanese Prime Minister Shinzo Abe and South Korean President Moon Jae-in for lunch. 鈥淭olerance for this disgraceful practice must end now.鈥

Hours later, Kim branded Trump as 鈥渄eranged鈥 and warned that he will 鈥減ay dearly鈥 for his threat to 鈥渢otally destroy鈥 the North if it attacks. The rare statement from the North Korean leader responded to Trump鈥檚 combative speech days earlier where he not only issued the warning of potential obliteration for the isolated nation, but also mocked the North鈥檚 young autocrat as a 鈥淩ocket Man鈥 on a 鈥渟uicide mission.鈥

Returning insult with insult, Kim said Trump was 鈥渦nfit to hold the prerogative of supreme command of a country.鈥 He described the president as 鈥渁 rogue and a gangster fond of playing with fire.鈥 He characterized Trump鈥檚 speech to the world body on Tuesday as 鈥渕entally deranged behavior.鈥

The volley of insults continued Friday, as Trump sent out a predawn Twitter post berating Kim.

鈥淜im Jong Un of North Korea, who is obviously a madman who doesn鈥檛 mind starving or killing his people, will be tested like never before!鈥 the president tweeted.

Trump鈥檚 executive order expanded the Treasury Department鈥檚 ability to target anyone conducting significant trade in goods, services or technology with North Korea, and to ban them from interacting with the U.S. financial system.

鈥淔oreign financial institutions must choose between doing business with the United States or facilitating trade with North Korea or its designated supporters,鈥 the order says. It also issues a 180-day ban on vessels and aircraft that have visited North Korea from visiting the United States.

Trump also said China was imposing major banking sanctions, too, but there was no immediate confirmation from the North鈥檚 most important trading partner. China鈥檚 central bank would not take questions by phone Friday and did not immediately respond to a faxed request for comment.

Trump praised China for instructing its banks to cut off business with Pyongyang, but neither the Chinese nor Trump officials were ready to say so. Treasury Secretary Steve Mnuchin said he had spoken at length Thursday with the head of China鈥檚 central bank but 鈥淚 am not going to comment on confidential discussions.鈥

If enforced, the Chinese action Trump described could severely impede the isolated North鈥檚 ability to raise money for its missile and nuclear development. China, responsible for about 90 percent of North Korea鈥檚 trade, serves as the country鈥檚 conduit to the international banking system.

Trump said the China action he described 鈥渨as a somewhat unexpected move and we appreciate it.鈥

China remains leery of pressuring North Korea into collapse and has resisted cutting off its critical oil supplies, not wanting chaos on its border. Along with Russia, China wants the U.S. to seek dialogue with the North. American officials say the time isn鈥檛 right for any formal diplomatic process. Foreign Minister Wang Yi said Thursday that negotiations are the 鈥渙nly way out鈥 of the nuclear standoff.

Several news outlets this month have reported Chinese steps to restrict banking transactions, but the government hasn鈥檛 made a formal announcement. Asked for comment last week, the Foreign Ministry said China has always fully implemented U.N. sanctions on North Korea but opposes 鈥渦nilateral鈥 restrictions imposed by another country on Chinese entities. China鈥檚 embassy in Washington declined to comment Thursday.

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Associated Press writer Darlene Superville contributed to this report.