Looking Back: The Portland Annual Christmas Tree Lighting Ceremony Bomb Plot, November 26, 2010
Homeland Security Digital Library Blog 2012-11-26
Summary:

Today, November 26, 2012, is the second anniversary of the foiled terrorist plot to bomb Portland's annual Christmas tree lighting ceremony in Pioneer Courthouse Square. On that day in 2010, Mohamed Osman Mohamud, a naturalized US citizen from Mogadishu, Somalia, attempted to detonate a vehicle bomb near a packed Christmas lighting ceremony; however, the (fake) explosives he acquired for the attack were provided to him as part of an FBI sting operation.