The Symington Amendment (22 U.S.C. §2799aa-1) and Glenn Amendment (22 U.S.C. §2799aa-2) legally prohibit U.S. foreign aid to countries developing nuclear weapons outside IAEA safeguards or detonating nuclear devices.
https://history.state.gov/historicaldocuments/frus1977-80v19/d6
how much foreign aid did israel get after the illegally built a nuclear bomb and will they pay it back with interest?