U.S. President Donald Trump said on Wednesday that the "twisted dictatorship" in North Korea cannot blackmail the world.

Trump delivered remarks on foreign policy after he returned from his 12-day tour of Asia.

He said the goal is to "denuclearize" North Korea, adding that time is running out and the U.S. has made clear "all options remain on the table."

Trump further said that the U.S. and China agree that a "freeze-for-freeze" agreement with North Korea is not acceptable.

He was referring to a proposal, backed by both China and Russia, whereby North Korea would freeze its nuclear program in exchange for the U.S. and South Korea stopping military drills.

Trump said that Chinese President Xi Jinping recognizes that a nuclear North Korea is a "grave threat."

"We agreed that we would not accept a so-called freeze-for-freeze agreement like those that have consistently failed in the past," he added.

Trump's trip to Asia took place amid 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 North Korean leader Kim have exchanged insults, with North Korea denouncing Trump as a "mentally deranged U.S. dotard" and Trump referring to Kim as “Little Rocket Man”.

During his visit to South Korea, Trump warned the North not to test him.

"This a very different administration than the United States has had in the past," Trump said as he addressed South Korea's National Assembly. "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.