Mr. Trump earlier this week said North Korean aggression will lead to "fire and fury" of a kind the world hasn't seen before, and - after receiving criticism that those words could provoke nuclear war - doubled down on them Thursday, saying, "maybe that statement wasn't tough enough".
Though dwarfed by the U.S.' military, North Korea's is still one of the largest in the world, with 1.2 million active service members, nuclear weapons, and tens of thousand of artillery at its disposal.
Tension in the region has risen since the reclusive North, which staged two nuclear bomb tests a year ago and launched two intercontinental ballistic missile tests in July in defiance of world powers.
Despite the different tone Tillerson and others have taken on North Korea, Mr. Trump said Thursday there is no confusion in views in his administration.
US military strategists at the Pentagon have a military solution in place to address the growing threat emanating from North Korea, but they are holding their fire in favor of ongoing diplomatic efforts by Washington and its allies, Defense Secretary James Mattis said Thursday.
"But Guam's former delegate to Congress, Robert Underwood, says he's concerned the 160,000 people of Guam are getting forgotten with President Donald Trump's escalating rhetoric toward North Korea". Trump threatened North Korea with "fire and fury" in return.
Trump has said he would not allow Pyongyang to develop a nuclear weapon capable of hitting the United States.
The official, who spoke to Newsweek on the condition of anonymity, said war game scenarios conducted by the USA and South Korea indicated that substantial time would be required to move military assets for an attack on the state. "But at the same time, our defenses are robust" and ready to take on any threat posed by the North Korean regime, Mr. Mattis said.
The President's comments on Tuesday have been the backdrop to a week of growing tensions on the Korean peninsula.