The Madrid train bombing on March 11, 2004, was an Al Qaeda operation and connected to the 9/11 attack, causing deep divisions in Spain. The aftermath led to the creation of the Department of Homeland Security and the National Counterterrorism Center in the US.
Key Points
Connection between Madrid train bombing and 9/11 attack
Misattributions of blame in Spain
Importance of US and Europe working together against terrorism
Pros
Increased awareness of terrorism threats
Creation of counterterrorism agencies like DHS and NCTC