Germany didn’t invade Iraq, so we know it couldn’t be Islamists:

Aug. 18 (Bloomberg) — Two suitcases containing bottles of gasoline, propane gas and a detonating device that were found abandoned in German regional trains last month were bombs primed to go off and kill a “high number’’ of people, police said.
“We’re accusing as yet unknown suspects of having tried to ignite unconventional flammable and explosive devices on July 31, 2006, in the cities of Dortmund and Koblenz with the aim of killing a high number of people,’’ Federal Prosecutor Rainer Griesbaum said at a press conference in Wiesbaden, Germany, today. The perpetrators are suspected of being members of a “domestic terrorist organization,’’ Griesbaum said.