President Trump ordered a widening of American sanctions on North Korea on Thursday to further choke off its trade with the outside world, in what some experts described as perhaps the most sweeping set of punitive economic measures enacted by the United States in many years.

A new executive order signed by Mr. Trump aimed to cut North Korea out of the international banking system while targeting its major industries and shipping. The move suggested that for now, at least, the president was still committed to applying economic pressure rather than military action, despite his vow this week to “totally destroy North Korea” if the United States were forced to defend itself or its allies.

“North Korea’s nuclear weapons and nuclear development is a grave threat to peace and security in our world, and it is unacceptable that others financially support this criminal, rogue regime,” Mr. Trump said as he hosted President Moon Jae-in of South Korea and Prime Minister Shinzo Abe of Japan for lunch in New York. “The brutal North Korean regime does not respect its own citizens or the sovereignty of other nations.”

The action came amid news reports that China’s central bank had instructed the country’s banks not to do new business with North Korea and to wind down old loans, in keeping with United Nations sanctions. As North Korea’s dominant economic partner, China holds the most sway with Pyongyang, but it remained unclear if its latest action would be enforced enough to have any real impact.