You didn't have to take their word for it. It was self-evident from the fact they never did anything like this before, and now they are.

Notably, the previous guy issued a religious decree against the development of nuclear weapons. Despite American's favorite propaganda tool for manufacturing consent, "but the WMDs", we have no reason to believe that was ever actually being violated. But you'd better believe it will be now if they think they can pull it off.

There is a difference between not doing something and being unable to do something. Clearly there were able but only showed it now and their previous claim was BS (again, assuming those missiles did fly "far").

No-one believes that Iran is not pursuing nuclear weapons, either... or that they wouldn't if they had developed the capability.

Ayatollah Khomeini admitted that he had lied about plans to make Iran democratic.

This practice is known as taqqiya. It’s ok to lie if you’re deceiving the enemy.

Do the missiles Iran has been raining down on other countries for decades not count as WMDs?