Bruce's lengthy statement continued, "Prior to the United States' successful military operation, Iran was amassing a growing stockpile of highly enriched uranium for which there was no credible peaceful purpose, and it was the only state producing highly enriched uranium, up to 60%, that does not have nuclear weapons."

The Iranian government has suspended cooperation with the U.N.'s International Atomic Energy Agency until the security of Iran's nuclear facilities and activities is assured.

The decision means that international inspectors will not be able to oversee sites. Experts have warned that Tehran could revive plans to build a bomb.