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President Donald Trump labeled brutal North Korean dictator Kim Jong Un "a pretty smart cookie" in a wide-ranging interview aired Sunday.

“At a very young age, he was able to assume power. A lot of people, I'm sure, tried to take that power away, whether it was his uncle or anybody else. And he was able to do it. So obviously, he's a pretty smart cookie,” Trump told CBS News in an interview on "Face the Nation."

“But we have a situation that we just cannot let — we cannot let what's been going on for a long period of years continue,” he added.

The interview, conducted Saturday, comes a day after North Korea test-launched what U.S. officials said was a short-range ballistic missile, a test prohibited by United Nations sanctions. The missile blew up shortly after launching, officials said.

Trump praised his relationship with Chinese President Xi Jinping as “very good” and rebuffed criticism over backing down from his oft-repeated campaign-trail promise to label China a “currency manipulator.

Trump reiterated in the Sunday interview that he believed China had stopped manipulating its currency, and stressed the importance of working with the nation over the threat of North Korea.

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North Korea's leader Kim Jong Un watches a military drill in this handout photo by state-run Korean Central News Agency (KCNA) on April 26, 2017. KCNA via Reuters

"I believe that President Xi is working to try and resolve a very big problem, for China also," Trump said, adding, “And that's North Korea. Can you imagine if I say, 'Hey, by the way, how are you doing with North Korea? Also, we're going to announce that you're a currency manipulator tomorrow.'"

Trump later added that the issue of North Korea was "maybe more important than trade."

“Trade is very important. But massive warfare with millions, potentially millions of people being killed? That, as we would say, trumps trade,” he said.

Related: National Security Chief Tells S. Korea U.S. to Pay for Antimissile System: Official

But Trump then questioned whether China could have potentially had a hand in meddling with the 2016 U.S. presidential election, despite U.S. intelligence agencies saying they believe the Russian government was involved in a covert campaign to attempt to influence the election.

President Donald Trump on April, 29, 2017. Carolyn Kaster / AP

"Knowing something about hacking, if you don't catch a hacker, okay, in the act, it's very hard to say who did the hacking," he said. "With that being said, I'll go along with Russia. Could've been China, could've been a lot of different groups."

Related: Trump Warns of Possible 'Major, Major Conflict' With North Korea

Trump then added that “we have to find out what happened,” and that he and his campaign “had nothing to do” with any potential election meddling.

Committees in both houses of Congress are currently investigating Moscow's involvement in the election as well as links between Russia and various Trump allies.

And as Trump marked his 100th day in office, he said he was "thoroughly enjoying" the job, and that while it was tough, he claims he's had jobs that were tougher.

"Well, it's a tough job. But I've had a lot of tough jobs. I've had things that were tougher, although I'll let you know that better at the end of eight years," he said.

Before becoming president of the United States, Trump was a real estate developer for most of his career after joining his father's company out of college, with stints as reality-TV star, sports-league owner, and writer. He is also in the World Wrestling Entertainment Hall of Fame.