What drove Fort Hood gunman to open fire?

Aired: 4/3/2014 | 0:12:31 | Clip
Army officials shed new light on the suspected gunman believed to have perpetrated the second mass shooting at Fort Hood in five years. Three people were killed and 16 wounded before Ivan Lopez, an Iraq veteran, killed himself. Judy Woodruff talks to Phillip Carter of the Center for a New American Security and retired Brig. Gen. Stephen Xenakis.