Hart says national security requires international ties

Former Democratic U.S. Sen. Gary Hart, who co-chaired a commission that warned in 1999 that the U.S. could face a catastrophic terrorist attack.

Guests

• Gary Hart: Former Colorado senator and two-time Democratic presidential candidate. Hart is currently a professor at the University of Colorado. His latest book is "The Shield and the Cloak: The Security of the Commons." He made his comments at the Commonwealth Club of California.