For the first time, a U.S. police officer has been charged with aiding ISIS

A law enforcement officer walks on the street outside the home of Nicholas Young, a Washington Metro Transit Officer, Wednesday, Aug. 3, 2016, in Fairfax, Va., Young was arrested at Metro's headquarters in Washington and charged with a single count of attempting to provided material support to a terrorist group. (AP Photo/Pablo Martinez Monsivais)
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A law enforcement officer walks on the street outside the home of Nicholas Young, a Washington Metro Transit Officer, Wednesday, Aug. 3, 2016, in Fairfax, Va., Young was arrested at Metro's headquarters in Washington and charged with a single count of attempting to provided material support to a terrorist group. (AP Photo/Pablo Martinez Monsivais)

A veteran Washington, D.C., police officer has been arrested and charged with providing material support to ISIS.

The U.S. Department of Justice said 36-year-old Nicholas Young conspired with an FBI informant to help the terrorist group by purchasing gift cards to fund mobile messaging accounts that ISIS uses to recruit potential soldiers.

Young had been a D.C. Metro Transit police officer since 2003. He was arrested Wednesday, making him the first American law enforcement officer charged with being involved with ISIS.

Authorities said there was never any danger to the D.C. Metro system because they were keeping a close watch on Young.

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Young was well-known to counterterrorism investigators, authorities said. Two of his acquaintances pleaded guilty to terrorism charges, and Young has been under investigation for years.

Court records show that Young traveled to Libya in 2011 and sympathized with Nazis and Islamic extremists. If convicted, Young faces a maximum sentence of 20 years in prison.

This video includes clips from ISIS, WRC-TV and WTTG.