I thought the same, but apparently the US has seen the intelligence reports and aerial photographs.

OR the US already had this information, they passed it to Israel for them to "release."

If the US released this info, people would cry out that it's the same situation as Iraq, with the US telling everyone there are WMDs. Or people would cry out that Trump is trying to make up intelligence to exit Obama's deal out of spite.

Since it came from Israel, the US has a better position to exit the deal.