A newly released U.S. intelligence report says that even a full-scale American war with Iran would likely not bring down the country’s government.

According to The Washington Post, citing three sources, the findings cast doubt on the Trump administration’s claim that such a war could be wrapped up in four to six weeks.

The assessment was finalized just a week after the joint U.S.-Israeli strike that killed Iran’s leader, Ali Khamenei.

It also concludes that a takeover by Iran’s fragmented opposition groups is unlikely.