U.S. President Donald Trump warned Tuesday that he will counter North Korea with "fire and fury" if the reclusive country further endangers the United States.

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

trump(getty)

 (Getty)

"He has been very threatening beyond a normal statement," Trump said of North Korean leader Kim Jong Un. "As I said, they will be met with fire, fury and, frankly, power, the likes of which this world has never seen before."

The comments came hours after the Washington Post reported that North Korea has successfully produced a miniaturized nuclear warhead that can fit inside missiles, citing a confidential U.S. assessment.

The daily said U.S. officials have concluded in their assessment completed by the Defense Intelligence Agency last month that Pyongyang has crossed a key threshold on the path to becoming a full-fledged nuclear power.

It also said the United States calculated in another intelligence assessment last month that up to 60 nuclear weapons are now controlled by Kim. Some independent experts believe the number of bombs is much smaller.

nkorea4(Korean Central Television)

(Korean Central Television)

An annual report released by the Japanese Defense Ministry this week also pointed out that the country could have achieved miniaturization.

"The IC (intelligence community) assesses North Korea has produced nuclear weapons for ballistic missile delivery, to include delivery by ICBM-class missiles," the assessment states, in an excerpt read to the Washington Post.

It is not yet known whether North Korea has successfully tested the smaller design, although the country officially claimed last year to have done so, the paper said.

North Korea fired an intercontinental ballistic missile on July 4, followed by another ICBM test-firing on July 28, prompting the U.N. Security Council to impose fresh sanctions on Pyongyang that aim to slash the reclusive country's $3 billion annual export revenue by a third.

Pyongyang said Monday the U.S.-led punitive action constitutes a "flagrant infringement upon its sovereignty and an open challenge to it," adding the resolution will be categorically rejected.

The sanctions resolution is the seventh the Security Council has imposed on North Korea since 2006, when the country carried out its first nuclear test.

The resolution bans the country from exporting coal, iron, iron ore, lead, lead ore and seafood so as to curb funding sources for its nuclear and missile ambitions.

It also forbids U.N. member countries from increasing the number of North Korean laborers abroad. The majority of such workers are in Russia and China.