From HSToday:

Transportation Security Administration (TSA) Administrator John S. Pistole told a Senate committee that no perfect solution exists to entirely eliminate risk. He was discussing the agency’s recent efforts to adopt a risk-based approach to transportation security. “As I have testified previously, it is not possible to eliminate risk altogether so our efforts must remain focused on managing and mitigating that risk. This is the most appropriate and sustainable model for TSA,” Pistole told the Senate Committee on Commerce, Science, and Transportation.