Former vice president Dick Cheney said Sunday that Sen. Rand Paul (R-Ky.) was wrong to suggest that the government's recently revealed sweeping surveillance techniques are an invasion of Americans' privacy.

"Two-thirds of the Congress wasn't here on 9/11, or for that period immediately after when we got into this program," Cheney said on "Fox News Sunday." He later added: "When you consider the possibility of somebody smuggling something like a nuclear device into the United States, it becomes very, very important to gather intelligence on your enemies and stop that attack before it ever gets launched."

Cheney defended a National Security Agency program to collect phone records from millions of Americans, about which Paul has expressed deep concerns. The Kentucky senator announced last week that he has taken steps toward bringing legal action against the government over its surveillance efforts.