Upvote:2
The US did notice the preparations at the time. I believe that the exact details of the diplomatic communications are still controversial. And of course the Iraqi decisionmaking structures were somewhat dysfunctional.
Regarding your second question, the current US intelligence sources are obviously classified, but I would assume that current intelligence on the Iranian forces is no worse than 1990s intelligence on the Iraqis. I'm not prepared to guess about the Saudis.