US President Donald Trump says US nuclear arsenal is 'far powerful than ever before'

US President Donald Trump speaking about North Korea at a meeting with administration officials in Bedminster, New Jersey, August 8, 2017. (Photo by AFP)

US President Donald Trump has boasted about the strength of the US nuclear arsenal, saying the country’s nuclear weapons are “more powerful than ever,” in a fresh warning to North Korea over its nuclear and missile program.

In a series of tweets on Wednesday, Trump said his first presidential order was to modernize the US nuclear arsenal, but said he hoped it would never be used.

"My first order as President was to renovate and modernize our nuclear arsenal. It is now far stronger and more powerful than ever before," Trump wrote on Twitter from New Jersey, where he is on vacation for two weeks.

"Hopefully we will never have to use this power, but there will never be a time that we are not the most powerful nation in the world!"

Trump ordered the Pentagon to review ways to modernize and strengthen US nuclear capabilities in January, though it is not clear if it was his "first order as president," as he claims.

The US Defense Department started a review of the new nuclear policy in April, but it is unlikely that any major changes or improvements have taken place since the review started.

Trump’s comments came a day after he warned North Korea that any threat to the United States would be met with "fire and fury".

"And as I said they will be met with fire, fury and frankly power, the likes of which this world has never seen before," he said.

Just hours after Trump made the threat, North Korea said it is considering plans for a missile strike on the US Pacific territory of Guam.

Trump's "fire and fury" comments triggered expressions of concern from some US lawmakers, as well as from China and several US allies.

Trump ratcheted up his war of words even as his top diplomat said there was no immediate threat of danger.

US Secretary of State Rex Tillerson said that he did not believe "there is any imminent threat" to Guam or other US targets and hoped that diplomatic pressure would prevail in the crisis.

US officials have repeatedly said this year that military action against the North was an "option on the table" to stop North Korea's nuclear and missile programs.

The Washington Post, quoting parts of a Defense Intelligence Agency analysis, reported Tuesday that North Korea crossed a major threshold by successfully producing “nuclear weapons for ballistic missile delivery."

North Korea carried out two tests of intercontinental ballistic missiles last month. Pyongyang claimed that its latest missile, test-fired on July 4, can deliver a "large, heavy nuclear warhead" to the US mainland.

The UN Security Council passed a resolution on Saturday slapping sweeping sanctions on the North following the launch of the intercontinental ballistic missile.