President Donald Trump issued a stark warning to North Korea during his address Wednesday to South Korea's National Assembly, warning that provocative action would amount to a "fatal miscalculation" under his administration.
He cast himself as more willing than previous US presidents to use military force against Pyongyang should they continue threatening the United States and its allies.
"This a very different administration than the United States has had in the past," Trump said. "Do not underestimate us. And do not try us."
Trump delivered a stern and personal message to North Korean dictator Kim Jong Un, warning that continued nuclear provocations would result in his regime's destruction.
"The weapons you are acquiring are not making you safer, they are putting your regime in grave danger," Trump said in what he called a "direct" message to Kim.
"Every step you take down this dark path increases the peril you face," Trump said. "North Korea is not the paradise your grandfather envisioned. It is a hell that no person deserves."
Trump called for a "complete and verifiable denuclearization" of the Korean peninsula.
"All responsible nations must join forces to isolate the brutal regime of North Korea to deny it any form of support, supply, or acceptance," he said.
Trump also drew a stark contrast Wednesday between South Korea and North Korea, saying that South Korea's economic growth is proof that the North Korean experiment has failed.
"When the Korean War began in 1950, the two Koreas were approximately equal in GDP per capita, but by the 1990s South Korea's wealth had surpassed North Korea by more than 10 times. And today the South's economy is over 40 times larger," Trump said. "You're doing something right."
"North Korea is a country ruled by a cult. At the center of this military cult is a deranged belief in the ruler's destiny to rule as a parent protector over a conquered Korean Peninsula," Trump said. "The more successful South Korea becomes the more successfully you discredit the dark fantasy at the heart of the south Korean regime."
Trump also contrasted the atrocious human rights conditions in North Korea with the freedoms South Korean citizens enjoy.
Near the front line of the world's tensest standoff Trump formally articulated his views of a region on edge during an address at South Korea's National Assembly.
North Korea's provocations have provided the underpinning for Trump's intensive talks in Asia at the start of his marathon tour of the continent. He received support in Japan for his combative stance, but in Seoul -- positioned 35 miles from the highly fortified border with the North -- Trump's fiery rhetoric has been met with unease.
His mission inside the soaring assembly hall was to convince his audience of Korean lawmakers, plus the broader region, that he's committed to preventing the type of annihilation that many fear is possible if Trump's language is misconstrued.
His remarks put the current conflict into historical context, stressing the half-century alliance between the US and South Korea while encouraging other countries in the region -- namely, China and Russia -- to step up their efforts to isolate North Korea.
Meanwhile, Pyongyang was closely watching Trump's key speech, according to North Korean officials authorized to speak to CNN on behalf of the regime.
The officials told CNN's Will Ripley ahead of the address that North Korea is not yet interested in talks with the United States despite Trump's conciliatory tone in South Korea. US officials point out three American citizens are currently in North Korean custody, and any diplomacy would also need to involve discussions for their release.
According to officials in North Korea and the United States, diplomatic channels are still closed after Trump's fiery UN speech in September. However, North Korea won't rule out future talks, but still feels the need to prove their nuclear capabilities, which means more tests, the officials said.
At no other point on his 13-day tour of Asia will Trump have a similar opportunity to lay out at length his plan to help secure American allies while also pursuing aggressive trade policies he believes will put the United States on fairer footing.
Drafts of the speech were in the works for weeks, officials say, with input from Trump's top national security aides like Secretary of State Rex Tillerson and national security adviser H.R. McMaster. Trump's speechwriter Stephen Miller is accompanying the President in Asia.
'Ultimately, it will all work out'
During a series of public appearances in and around the South Korean capital on Tuesday, Trump defended his provocative threats toward Kim Jong Un. But he declined to repeat the type of fiery bombast which has helped ratchet up tensions here.
"Ultimately, it will all work out," Trump said ahead of a briefing at a US Army garrison near Seoul shortly after landing in South Korea on Tuesday. "It always works out. It has to work out."
Later, at a news conference alongside South Korean President Moon Jae-in, Trump declined to say whether he's entirely ruled out diplomatic talks with Pyongyang, a move he'd previously derided as a waste of time.
And while he again declined to rule out use of military force in countering North Korea's threats, he appeared less willing to provoke the communist regime than he has from the United States.
"We have many things happening that we hope -- in fact, I'll go a step further -- we hope to God we never have to use," he said.
That sense of restraint hasn't always colored Trump's remarks about the North Korea crisis. Over the summer, he dramatically scaled up his threats, vowing to rain "fire and fury" on the communist regime if their provocations continue.
Later, he demeaned the country's dictator at the United Nations General Assembly, terming him "rocket man" at the gathering of world leaders.
Each time, Kim has responded in kind, lambasting Trump as a senile leader who was putting the world's security as risk. Since Trump assumed office, he has scaled up his country's ballistic missile launches, and conducted a massive underground nuclear test in September.
In Asia this week, Trump has tamped down the bitter back-and-forth, avoiding direct insults of young and brash leader just across the border. His tame by comparison remarks have warned North Korea that the US era of "strategic patience" was over, but declined to threaten all-out war.
"Hopefully, something very successfully (will be) worked out on that," he said during talks with Moon on Tuesday.
Moon, meanwhile, expressed optimism that Trump could help ease his country's concerns about the persistent spat with North Korea, despite his own differences with Trump's approach. Trump has accused Moon of appeasement, and scoffed at his desire to open talks with North Korea in a bid to cool tensions.
Speaking Tuesday, Moon said he hoped Trump could help "relieve some of the anxiety that the Korean people have due to North Korea's provocations."
South Koreans gathered to mark Trump's address, with local police protectively lining the streets.
CNN's Paula Hancocks reports: "More Trump supporters than protestors today. Some traveled from other side of the country to welcome him."