U.S. President Donald Trump issued a stark warning to North Korea as he addressed South Korea's National Assembly on Wednesday (local time).

"This a very different administration than the United States has had in the past," Trump said, according to CNN. "Do not underestimate us. And do not try us."

He warned that provocative action on the part of Pyongyang would amount to a "fatal miscalculation" under his administration, casting himself as more willing than previous presidents to use military force against Pyongyang should they continue threatening the United States and its allies.

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," he added. "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, saying, according to CNN, "All responsible nations must join forces to isolate the brutal regime of North Korea to deny it any form of support, supply, or acceptance.”

"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," said the president. "The more successful South Korea becomes the more successfully you discredit the dark fantasy at the heart of the south Korean regime."

Trump's speech in Seoul is part of his 13-day tour of Asia which began Sunday, and which is expected to focus mostly on the North Korean threat.

There have been ongoing tensions with North Korea in recent months. The isolated country sparked global alarm by conducting a sixth nuclear test and test-launching missiles capable of reaching the U.S. mainland.

In addition, Trump and Kim have exchanged insults, with North Korea denouncing Trump as a "mentally deranged U.S. dotard".

Trump has mocked Kim as "Little Rocket Man" and has vowed to rain "fire and fury" down on the North if it threatens the United States or its allies.

In an interview earlier this week, however, Trump softened his tone and said he would "certainly be open" to meeting with Kim.

Ahead of Trump's speech to South Korea's National Assembly, North Korean officials authorized to speak to CNN said the risk of war had never been higher.

"Over decades of bilateral confrontation, never, ever has the situation on the Korean peninsula been this acute with the real military confrontation and risk of another Korean War looming over the horizon," the officials told the network.

While North Korea will be closely watching and listening to President Trump's words, the regime is downplaying the impact of his speech on their actions, they stressed.

"We don't care about what that mad dog may utter because we've already heard enough," said the officials.