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Sheriff David Clarke joined Stuart Varney today to react to the arrest of a Washington, D.C., Metro Transit police officer for attempting to provide material support to ISIS.

Sheriff Clarke said this incident reinforces the need for Congress to do a "reset" on how domestic intelligence is handled in the U.S., calling the current system "inefficient and ineffective."

He pointed out that the FBI had been investigating this officer, Nicholas Young, since 2010.

He said that lengthy investigations like that enable terrorist sympathizers like Omar Mateen, Nidal Hassan and the Tsarnaev brothers to be flagged but then slip off the FBI's radar.

"There are tens of thousands, probably more, radicalized Americans here in the United States. If you take six years on each one, some them will be in their 90s by the time we get around to it," Sheriff Clarke said.

He called for our domestic intelligence agencies to use a "wartime model," in which anyone who declares allegiance to ISIS is immediately categorized as an "enemy combatant."

He explained that would allow the authorities to bring these radicalized individuals in for "thorough debriefings," followed by increased surveillance by intelligence analysts.

"If you pledge allegiance to [the] Islamic State, you are an enemy combatant," Sheriff Clarke stated. "No more waiting for them to commit a crime. This is ineffective. It's not going to work."

Watch more above.

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