Philadelphia teen facing charges in FBI terrorism investigation

A Philadelphia teenager is accused of stockpiling materials used to construct explosive devices that authorities say they feared he planned to use in attacks on unspecified American targets.

Driving the news: Philadelphia District Attorney Larry Krasner detailed multiple charges Monday against a 17-year-old, whose name isn't being released, following an FBI terrorism investigation.

• The charges include criminal conspiracy, possessing weapons of mass destruction and arson.
• The teen was arrested late last week after authorities learned that he was communicating with Katibat al Tawhid wal Jihad (KTJ), a global terrorist organization tied to Al Qaeda, FBI special agent Jacqueline Maguire said at the news conference Monday.

In the weeds: The teen received "guidance" on how to construct bombs and "appeared to be taking steps" to travel overseas to join or support the terrorist organization, Maguire said.

• Authorities allege that the teen recently purchased tactical equipment, wiring, chemicals, and devices commonly used as remote detonators.
• He also had access to a "significant number of firearms" and researched potential targets, authorities said, without naming specific locations.

What they're saying: "This was now a situation where we believed public safety was at risk," Maguire said.

What we're watching: Kranser's office is seeking to move the teen's case to adult court.