Chairman of the Joint Chiefs of Staff Admiral Mike Mullen (L) and Defense Secretary Robert Gates (R) testify during a hearing of the House Appropriations Defense Subcommittee on the budget for the Defense Department on Capitol Hill in Washington March 2,
Chairman of the Joint Chiefs of Staff Admiral Mike Mullen (L) and Defense Secretary Robert Gates (R) testify during a hearing of the House Appropriations Defense Subcommittee on the budget for the Defense Department on Capitol Hill in Washington March 2, 2011. REUTERS

Establishing a no-fly zone over Libya would require widespread bombings to destroy Libyan air defenses first, a top U.S. defense official said on Wednesday.

It's a big operation in a big country, Secretary of Defense Robert Gates told a House subcommittee.

Gates, re-iterating comments made by other military officials this week, said enforcing a no-fly zone would be an extensive military operation.

Let's just call a spade a spade, he said.

A no-fly zone begins with an attack on Libya to destroy the air defenses. That's the way you do a no-fly zone. And then you can fly planes around the country and not worry about our guys being shot down. But that's the way it starts.

[T]he no-fly zone is an option that is being actively considered, White House spokesman Jay Carney said on Tuesday.

The United States has experience with enforcing no-fly zones. It previously one over Iraq for more than a decade.