As someone who once worked around nuclear weapons, not on them, just around them, there is nothing 'hypothetical' about the initials 'WMD'. There is a great difference between a functional nuclear explosive device and a functional nuclear weapon. I used to work around the second: functional nuclear weapons. Back in WW II, before Fat Man and Little Boy, we had several functional nuclear explosive devices. The bombs Fat Man and Little Boy were those devices with the excess trimmed and finally packaged into deliverable forms. The CARRIERS of those forms could be a gravity driven bomb, a cruise missile, or a ballistic missile.
To date, the best way to know if an indigenously designed and built nuclear explosive device, not yet weapon, is functional, meaning to go ka-boom, is to actually detonate the device. Iraq never test detonated a device. So if YOUR perception of the initials 'WMD' mean a functional nuclear weapon, that mean the entire sanction and inspection regime upon Iraq was illegal from the start. But since the UN was already in Iraq and supported sanctions, that mean the initials 'WMD' cannot be as simplistic as you perceived. Here is a teaser for you...
It is clear that even though ElBaradei was speaking in general principles, global concerns about nuclear weapons are far more in-depth than your simplistic perceptions of what is a 'weapon of mass destruction'. The UN is concerned with components, programs, and even people associated with nuclear technology, let alone with nuclear weapons.