The top Democrat on the House Intelligence Committee said Wednesday that the most serious national security crisis President Trump will face will be North Korea during his first term.

“I can say that probably the most serious national security crisis this president is going to face is when the regime gets to the point of when it can miniaturize a nuclear device and put it on an intercontinental ballistic missile. That point will probably come during this four-year term of the president,” Rep. Adam Schiff, D-Calif., said in an interview on “CBS This Morning.”

“That challenge is coming if something doesn’t change,” he warned, adding that China is the key to this issue but even that may not be enough to deter North Korea.

The comments came after he was asked whether he could confirm a Bloomberg report that says analysts estimate that North Korea now has 10 to 25 nuclear weapons. Schiff said he couldn’t confirm the specifics because then he’d be revealing classified information.

All of the U.S. military options are “terrible,” said Schiff, who also said that Mr. Trump is on “very dangerous ground with all the saber-rattling.” He warned the president to be very careful not to explicitly or even implicitly draw a red line when it comes to North Korea.

North Korea had tested a KN-17 missile over the weekend, CBS News national security correspondent David Martin reported Monday. The test failed, with the missile blowing up immediately, according to U.S. Pacific Command. The U.S. had been considering military options against North Korea because of its nuclear program.

As for the investigation into Russia’s meddling in the U.S. election, Schiff said that the Intelligence Committee is “back on track” after its chairman, Rep. Devin Nunes, R-California, recused himself from the probe due to ethics issues. Schiff said Wednesday that Nunes had “cast a real cloud over the committee.”

Schiff emphasized that he wants to make sure that the panel try to do as much as it can in open session.

“I don’t think we’ll have the public’s confidence if they haven’t seen how we have proceeded with the investigation, so I’m hoping that where we can, we do as much of this as possible in public,” he said.