The Pentagon, which had said strikes “obliterated” Iranian nuclear sites, now puts the delay on Iran's nuclear ambitions at one to two years.

The new assessment contrasted with U.N. agency view that Iran could resume enriching uranium in a “matter of months.”

The Pentagon on Wednesday sharpened its assessment of Iran's nuclear program, declaring that Iran's ability to build a nuclear weapon following the U.S. strike on its nuclear facilities is "closer to two years" away.