Donald Trump says "only one thing will work" to stop North Korea's nuclear ambitions.
The US President took to Twitter on Sunday morning (NZ time) to say "talking... agreements made and massive amounts of money paid hasn't worked".
"Agreements [were] violated before the ink was dry, makings fools of US negotiators. Sorry, but only one thing will work!"
"We have not declared war on North Korea and frankly the assertion of that is absurd," White House spokeswoman Sarah Sanders said.
Early in September US Ambassador Nikki Haley told the United Nations that Kim Jong-un was "begging for war".
"War is never something the United States wants. We don't want it now. But our country's patience is not unlimited. We will defend our allies and our territory," Ms Haley said at the time.
Last week Mr Trump said US Secretary of State Rex Tillerson was "wasting his time" trying to talk to the North Korean regime.
North Korea is believed to be prepping to test a missile it claims could reach the west coast of the US.