North Korea staged a mass rally in the heart of its capital on Saturday to hail leader Kim Jong Un's pledge to fight against U.S. President Donald Trump.

About 100,000 people packed Pyongyang's Kim Il Sung Square in the late afternoon in a show of support for Kim's statement vowing to have Trump "pay dearly" for his recent U.N. speech.

The statement was read out during the rally and the participants, including senior members of the Workers' Party of Korea, called for retaliatory measures against the United States.

In the first-ever statement issued in the name of the North Korean leader, he said, "Now that Trump has...insulted me and my country in front of the eyes of the world and made the most ferocious declaration of a war...we will consider with seriousness exercising of a corresponding, highest level of hard-line countermeasure."

"It is really idiotic if the U.S. president thought that he could shock us with such nonsensical remarks," Kim Yong Il, 29, a university student, told Kyodo News.

The participants also marched in the huge square with placards bearing pugnacious slogans such as "nuclear thunder to the United States."

The ruling party and its military also held similar rallies on Friday, when Kim's statement was reported by the country's official media.

The extraordinary statement has raised fears that North Korea could conduct yet another major weapons test in the days ahead.

But a number of North Korea watchers have pointed out that Kim's use of the words "consider with seriousness" suggest that his country's next action may be conditional, depending on Trump's future stance.

Trump, however, said in a Twitter message on Friday night that Kim, "who is obviously a madman who doesn't mind starving or killing his people, will be tested like never before!"

The international community has already condemned North Korea multiple times for its flurry of nuclear and missile tests.

Still, Trump's recent inflammatory and forthright comments on North Korea only escalated tensions.

In his debut address to world leaders at this year's U.N. General Assembly meeting on Tuesday, Trump said that if the United States is forced to defend itself or its allies, it will have "no choice but to totally destroy North Korea."

Trump even went on to mock Kim as "Rocket Man," on "a suicide mission for himself and for his regime."

In his conclusion to the statement, Kim, in return, said he will "definitely tame the mentally deranged U.S. dotard with fire," referring to Trump.

The rhetorical combat continues as many other countries are concerned about potentially more serious consequences as North Korea quickens the pace of developing a nuclear-tipped intercontinental ballistic missile.