SEOUL, South Korea — President Trump said after North Korea’s latest failed rocket launch that communist leader Kim Jong-Un will eventually develop better missiles, and “we can’t allow it to happen.”

In a taped interview broadcast Sunday on CBS’ “Face the Nation,” the president would not discuss the possibility of military action, saying: “It is a chess game. I just don’t want people to know what my thinking is.”

Separately, Trump’s national security adviser, Army Lt. Gen. H.R. McMaster, said North Korea’s most recent missile test represents “open defiance of the international community.” He said North Korea poses “a grave threat,” not just to the U.S. and its Asian allies, but also to China.

Speaking on “Fox News Sunday,” McMaster said it is important “for all of us to confront this regime, this regime that is pursuing the weaponization of a missile with a nuclear weapon.”

“This is something that we know we cannot tolerate,” McMaster said.

On Saturday, a North Korean mid-range ballistic missile broke up a few minutes after launch, the third test-fire flop this month. The program’s repeated failures over the past few years have given rise to suspicions of U.S. sabotage.

In the CBS interview, the president was asked why the North’s rockets keep blowing up.

“I’d rather not discuss it,” he said. “But perhaps they’re just not very good missiles. But eventually, he’ll have good missiles.”

“And if that happens, we can’t allow it to happen.”

Trump also called North Korea’s leader “a pretty smart cookie” for being able to hold onto power after taking over at a young age. “People are saying, ‘Is he sane?’ I have no idea,” the president said.

North Korean ballistic missile tests are banned by the United Nations because they are seen as part of the North’s push for a nuclear-tipped weapon that can hit the U.S. mainland.