Concept
Version 7
Created by Boundless
Collective Military Force
September 11 and Collective Defense
The 11 September attacks in the United States caused NATO to invoke its collective defense article for the first time.
Source
Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:
"National Park Service 9-11 Statue of Liberty and WTC."
http://en.wikipedia.org/wiki/File:National_Park_Service_9-11_Statue_of_Liberty_and_WTC.jpg
Wikipedia
Public domain.