Defining the 'Tipping Point' for Intervention in War

The Takeaway
All this week The Takeaway has followed the news out of Syria, where a horrific massacre at the hands of Syrian government troops in the village of Houla recently left 108 civilians dead, including a number of children, most murdered at close-point range. UN-Arab League Special Envoy Kofi Annan met with Syrian President Bashar al-Assad on Tuesday, and told the press, "I shared with President Assad my assessment that the six-point plan is not being implemented as it must." Are we at a tipping point in Syria?  Philip Gourevitch, author and staff writer for The New Yorker, has also covered a number of international conflicts. He examines tipping points for the United States throughout the last century.