Republican presidential candidate Donald Trump proposed a new strategy Wednesday for defeating terrorists like the Islamic State group: kill their families. Speaking about the United States' fight against ISIS on "Fox and Friends," Trump criticized President Barack Obama's previous comments that the militants had been contained. Trump said Obama "doesn't know what he's doing," and when the anchors pressed the mogul on his plan for ISIS, he said he "would knock the hell out of them."

"And the other thing is with the terrorists, you have to take out their families," Trump said. "When you get these terrorists, you have to take out their families. They care about their lives; don't kid yourself. But they say they don't care about their lives. You have to take out their families."

During the interview, Trump declared ISIS to be the U.S.'s No. 1 threat. He said he'd do his best to protect civilians in Syria but added that the thought the extremists were using people as shields. "We're fighting a very politically correct war," Trump said.

Trump, who is known for making politically divisive remarks, has used this sort of rhetoric before. He has rejected the idea of accepting Syrian refugees fleeing the violence into the U.S., instead proposing a "big, beautiful safe zone," and said he predicted terrorism because he could feel it. Last month, he called Obama "weak and ineffective," the Hill reported.

"Every time he sends troops over -- even if it’s a small number, like he’s sending another small number. He announced 50 last week -- he has a press conference to inform everybody he’s sending troops, and it's like they have a target on their back," Trump said on "Fox and Friends."

As of Wednesday, Trump was leading the field of GOP presidential candidates, with 34.4 percent of likely primary voters, according to the HuffPost Pollster. In second place was Sen. Marco Rubio, R-Fla., with 14.6 percent and retired neurosurgeon Dr. Ben Carson, with 13.9 percent.