US President Donald Trump escalated his rhetoric against North Korea tonight, suggesting he had "not been tough enough" when he warned the rogue regime faced "fire and fury".
Trump said North Korea should be "very, very nervous" about doing anything to the United States or its allies.
He said: "It's about time somebody stuck up for the people of this country and for the people of other countries. So if anything, maybe that statement wasn't tough enough."
The president was vague about what further action his administration might take, telling reporters: "You'll see. You'll see."
Trump added: "If North Korea does anything in terms of even thinking about attack of anybody that we love or we represent or our allies or us, they can be very, very nervous. Because things will happen to them like they never thought possible, OK? He's been pushing the world around for a long time."
"North Korea better get their act together or they are going to be in trouble like few nations have ever been in trouble." Kim Jong-un's regime had earlier dismissed Mr Trump's warning as "nonsense."
Trump, speaking at his golf course in New Jersey, responded: "I don't think they mean that. It's the first time they've heard it like they heard it. We'll always consider negotiations but they've been negotiating for 25 years."
Asked whether he would consider a pre-emptive strike, he said: "We'll see."
He also increased pressure on China to act to rein in North Korea, a strategy the Trump administration has long pursued.
Trump added: "I think China can do more, and I think they will."
Trump spoke after meeting with Vice President Mike Pence, Chief of Staff John Kelly, and National Security Adviser HR McMaster.
His comments came hours after the US sent a Navy destroyer close to an artificial island Beijing has built up in the South China Sea. China's foreign ministry said the move had violated international and Chinese law, and seriously harmed Beijing's sovereignty and security.
The USS John S. McCain sailed close to Mischief Reef in the Spratly Islands. A Chinese frigate sent radio warnings at least 10 times during what the US called a six-hour "freedom of navigation" operation.
It was the third such operation it has carried out since Trump took office.
Residents of the tiny US territory of Guam were warned last night they will have just 14 minutes warning if missiles are fired at them from North Korea.
North Korea has said it would have a plan ready by "mid-August" to fire four Hwasong-12 rockets into waters near the Pacific island, 3400km to its south.
Jenna Gaminde, Guam's Homeland Security spokeswoman, said village mayors and social media would be used to spread warnings.
She added: "If you hear the sirens, tune into local media, radio, print, television for further instructions. Our office will be notified from the military and will utilise all forms of mass communication to get the message out to the public."