Noem had joined federal immigration authorities Tuesday in New York City for the sweeps, which officials said were targeting violent criminals in major cities and elsewhere.
On Wednesday, Noem addressed the arrest of who she described as a "ringleader" of the Tren de Aragua gang during an appearance on "Fox & Friends."
"He had just been a part of a gun weapons exchange and was trying to buy grenades," Noem said. "Why would anybody in this country need to buy a grenade and go out and perpetuate violence?"
Sources in the Department of Homeland Security told Fox News on Tuesday that the suspected gang member, whom they identified as Anderson Zambrano-Pacheco, was arrested inside a Bronx apartment and charged with kidnapping, assault and burglary.