Two points should be made here. First, the claim that the NPT’s Article IV does not affirm the right of non-nuclear-weapons states to pursue indigenous development of fuel-cycle capabilities, including uranium enrichment, under international safeguards is flat-out false.
Article IV makes a blanket statement that “nothing in this Treaty shall be interpreted as affecting the inalienable right of all the Parties to the Treaty to develop research, production and use of nuclear energy for peaceful purposes without discrimination.” And it’s not just “countries such as Japan and Germany”—both close U.S. allies—which affirm that this includes the right of non-weapons states to enrich uranium under safeguards. The BRICS (Brazil, Russia, India, China, and South Africa) countries and the Non-Aligned Movement (whose 120 countries represent a large majority of UN members) have all clearly affirmed the right of non-nuclear-weapons states, including the Islamic Republic of Iran, to pursue indigenous safeguarded enrichment.
In fact, just four countries in the world hold that there is no right to safeguarded enrichment under the NPT: the United States, Britain, France, and Israel (which isn’t even a NPT signatory). That’s it.
Moreover, the right to indigenous technological development—including nuclear fuel-cycle capabilities, should a state choose to pursue them—is a sovereign right. It is not conferred by the NPT; the NPT’s Article IV recognizes states’ “inalienable right” in this regard, while other provisions bind non-weapons states that join the Treaty to exercise this right under international safeguards.