NBC News — Facing deep budget cuts, the U.S. will no longer be able to make up for the significant shortfalls that have plagued NATO's operations in Libya and Afghanistan, that's according to Secretary of Defense Leon Panetta.

Panetta made the comment wednesday during a speech before the opening of a NATO defense ministers' meeting in Brussels. This is Panetta's first visit to Europe after taking over the Pentagon's top job from Robert Gates in July.