President Donald Trump speaks at a campaign rally in support of Sen. Luther Strange, Sept. 22, 2017, in Huntsville, Ala. Brynn Anderson/AP President Donald Trump shot back at North Korean leader Kim Jong Un during a speech at a rally in Huntsville, Alabama, on Friday.

"We can't have madmen out there shooting rockets all over the place," Trump said, referring to Kim Jong Un. "And by the way, 'Rocket Man' should have been handled a long time ago. By Clinton. I won't mention the Republicans right? By Obama."

"This shouldn't be handled now, but I'm gonna handle it because we have to handle it," Trump continued. "'Little Rocket Man.' We're gonna do it because we really have no choice."

Trump's comments come a day after Kim Jong Un made a rare and personal statement, in which he likened Trump to a "frightened dog" and called him a "dotard." On Friday morning, Trump responded by calling Kim Jong Un a "madman" and threatened that he "will be tested like never before."

Although North Korean rhetoric is often exaggerated and contains offensive metaphors, its recent statement followed the country's largest nuclear test and Trump's first address before the UN General Assembly on Tuesday, where he decried the regime for its continued provocations.

"Now he's talking about a massive weapon exploding over the ocean, Pacific Ocean, which causes tremendous calamity," Trump said, referring to North Korean Minister of Foreign Affairs Ri Yong Ho's claim that his country was exploring the possibility of testing a hydrogen bomb in the Pacific.

President Donald Trump and North Korean leader Kim Jong Un appear on a television screen. Ahn Young-joon/AP

"Where that plume goes, so goes cancer, so goes tremendous problems," Trump continued. "And I want to tell you something, and I'm sure he's listening cause he watches every word, and I guarantee you one thing, he's watching us like he never watched anybody before. That I can tell you."

Trump also cast doubt on the possibility of bringing North Korea to the negotiating table, a move that would be at odds with the latest sanctions from the UN Security Council and another series of sanctions from the US.

"And maybe something gets worked out, and maybe it doesn't," Trump said. "Personally I'm not sure that it will."

"Other people like to say, 'Oh we want peace,'" Trump continued. "You know, they've been saying for now 25 years, 'We want peace, we want peace.' And then [Kim Jong Un] goes and just keeps going, going, going."

"But I can tell you one thing — you are protected," Trump said. "Nobody is going to put our people in that kind of danger."

Trump held the rally in support of Sen. Luther Strange, ahead of a runoff election against former Alabama Chief Justice Roy Moore, set for Tuesday. Strange was appointed after former Sen. Jeff Sessions was tapped by Trump to serve as Attorney General.

Watch a clip of the speech below: