A preliminary classified US report says the American bombing of three nuclear sites in Iran set back the country’s nuclear program by only a few months, according to officials familiar with the findings, reports The New York Times (NYT).

The strikes sealed off the entrances to two of the facilities but did not collapse their underground buildings, the officials said the early findings concluded.

The sources who spoke to the NYT clarified that although the targeted attacks using "bunker busters" managed to block access to two nuclear facilities, they did not destroy the main structures. This includes Fordow, the headquarters of Iran's nuclear program, which is built deep in a mountain, the media report.

The aforesaid report directly contradicts statements by US President Donald Trump, who said shortly after the strikes that the operation was a tremendous military success and that Iran's main uranium enrichment facilities had been completely destroyed.