and what was the level , Tehran research reactor before the revolution was designed to use 90% uranium , after the revolution because usa didn't provide us with the necessary uranium to work the reactor , with the help of Argentina we converted it so it can use 20% uranium , usa prevented Argentina to provide us the necessary uranium rods to work the reactor so we enriched uranium to that grade and turned it int power rods and used it in the reactor . completely legal under NPT , it was under the eye of IAEA .
till today the only weapon grade uranium traces found in iran was traces on the equipment we bought from Pakistan to start our program and the equipment were second hand and everybody knew that so no Iran didn't enrich uranium against NPT . if we build another reactor like original Tehran research reactor then we can legally enrich uranium up to 90% , if we build a reactor like Fukushima reactor that uses , mixture of plutonium and uranium as fuel we can legally reprocess the spent fuel and extract plutonium from them.
what you do with material and have a civilian use for them is important according to npt. its not even a violation of npt if you produce plutonium under IAEA observation and then sell it to someone who has a civilian use for it if you yourself don't have a civilian use for it . according to npt what is important diverting materials for nuke or not
there is a rule and procedure for anything, IAEA refer the violator to Board of Governors of the International Atomic Energy Agency, and they decide if violation is severe enough to warant more action they decide what to do , and if it can be solved in IAEA , if they decide it can't be solved there they refere the violator ti UNSC and its there that the fate of the violator must be decided. who is USA to single handedly decide what to do with anybody who violated NPT, who gave usa to be the police , Judge and executioner . it seems they really believe this