President Donald Trump on Friday warned North Korean leader Kim Jong-Un not to take any action against the US, its territories including Guam or its allies, warning he would regret such a move -- and "regret it fast."

Trump said Washington was looking "very carefully" at its military options, and that he hoped Kim had taken his words to heart in recent days -- just this morning, Trump said America's military was "locked and loaded." 

North Korea has said it is readying plans to launch missiles towards the US Pacific territory of Guam.

"I hope that they are going to fully understand the gravity of what I said, and what I said is what I mean," Trump told reporters. 

"If he does anything with respect to Guam or anyplace else that's an American territory or an American ally, he will truly regret it, and he will regret it fast."