WASHINGTON — President Donald Trump issued a stern warning Tuesday to North Korea, saying “fire and fury” await the rogue regime, should it further threaten the United States with nuclear action.

He delivered the statement with arms crossed, appearing defiant amid news reports that Pyongyang has successfully miniaturized a nuclear warhead that can fit on its missiles.

“North Korea best not make any more threats to the United States,” the president told reporters at his Bedminster, New Jersey, golf club. “They will be met with fire and fury like the world has never seen.”

He added of North Korean dictator Kim Jong Un: “He has been very threatening beyond a normal state, and as I said, they will be met with fire and fury — and frankly power — the likes of which this world has never seen before.”

He did not elaborate on how he may retaliate as commander in chief or what it means for U.S. troops on the peninsula and U.S. allies Japan and South Korea.

Trump was responding to reporters’ questions about North Korea during a meeting of his top aides on opioid abuse in the United States.

Kim has intensified his pursuit of nuclear capabilities, testing intercontinental ballistic missiles, to the alarm of many in Washington.

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Trump last week signed a bipartisan bill expanding sanctions on several U.S. adversaries. He had criticized the legislation for rolling back his executive power when it comes to ending or easing penalties on Russia, but he commended it for sending a message to North Korea and Iran, both of which harbor nuclear ambitions.

Sen. Dianne Feinstein (D-Calif.) called for “high-level dialogue” with Pyongyang over the threats.

“Isolating the North Koreans has not halted their pursuit of nuclear weapons,” she said in a statement. “And President Trump is not helping the situation with his bombastic comments.”

Sen. John McCain (R-Ariz.) also was critical, telling KTAR-FM radio: “I take exception to the president’s comments, because you got to be sure you can do what you say you’re going to do.”

Kellyanne Conway, counselor to the president, could not offer details about Trump’s message on North Korea, but she said she believed his remarks to be “very strong and obvious.”

Trump is in the midst of a 17-day working vacation, a part of which he’s spending at his New Jersey estate, but he will visit New York City early next week.

His focus Tuesday was not just international but domestic affairs, as he summoned senior advisers, including Conway and Health Secretary Tom Price, to his golf club to debrief him on the opioid epidemic gripping the country.

The president said he wanted young people steered away from ever using drugs in the first place.

“If they don’t start, they won’t have a problem. If they do start, it’s awfully tough to get off,” Trump said. “So if we can keep them from going on and maybe by talking to youth and telling them: ‘No good, really bad for you in every way.’ ”

The president vowed anew to win the war on drugs and indicated he may step up prosecutions toward that end.

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“At the end of 2016, there were 23 percent fewer federal prosecutions than in 2011, so they looked at this surge and they let it go by,” he said. “We’re not letting it go by.”

Though Trump’s commission to combat opioid abuse, a panel led by New Jersey Gov. Chris Christie, recommended earlier this month that the president declare a national state of emergency, Trump did not take that step Tuesday.