How would you comment on deterrence and defense in light of the statement below?

"Deterrence isn't what it used to be. In the second half of the twentieth century, it was the backbone of U.S. national security. Its purpose, logic, and effectiveness were well understood. It was the essential military strategy behind containing the Soviet Union and a crucial ingredient in winning the Cold War without fighting World War III. But in recent decades, deterrence has gone astray, and U.S. defense policy is worse for the change." (Betts, 2013)