Enriching the uranium isn't the same as building a weapon, though.
In what way may I ask? I unwittingly addressed that question in the intelligence report I linked to earlier.
1. Design and build an implosion trigger. Not easy to do.
2. Test that implosion trigger. Not easy to hide.
3. Build the bomb itself - combine the trigger and the uranium payload.
4. Test the bomb. Impossible to hide.
5. Build a delivery system. Impossible to hide.
6. Test the delivery system. Impossible to hide.