President Trump on Tuesday sternly warned North Korea against making threats to the U.S., responding to reports that Pyongyang has expanded its nuclear capabilities.

“North Korea best not make any more threats to the United States,” Trump told reporters at his New Jersey golf club.

“He has been very threatening beyond a normal state, and as I said they will be met with fire, fury and frankly power, the likes of which this world has never seen before.”

His provocative comments came after The Washington Post, citing a U.S. intelligence assessment, reported that North Korea crossed a major threshold in its quest to become a nuclear power by successfully producing a miniaturized nuclear warhead that can fit onto a missile.

If true, the development would cross the Trump administration’s red line on North Korea’s nuclear program.

ADVERTISEMENT

“If they had nuclear weapons that can threaten the United States, it's intolerable from the president's perspective,” national security adviser H.R. McMaster said in an interview that aired Saturday on MSNBC.

North Korea has been testing intercontinental ballistic missiles that could reach the continental United States. Over the weekend, the United Nations Security Council voted unanimously to sanction Pyongyang for the tests.

Even as the Post report alarmed Washington, North Korean leader Kim Jong Un’s ability to strike his adversaries with nuclear weapons remains shrouded in mystery.

It’s not clear whether the country has tested the miniaturized warhead successfully and it does not appear to have a reentry vehicle to prevent a nuclear-armed ICBM from burning up upon its descent from space.

- This story was updated at 5:27 p.m.