The diffusion of enrichment and reprocessing (E&R) technologies can increase the risk of the proliferation of nuclear weapons in several ways. First, enrichment and reprocessing facilities can produce nuclear materials – highly enriched uranium (HEU) and separated plutonium—that are directly usable in nuclear weapons. With such materials, a state could abrogate its nonprolifera - tion commitments and produce a nuclear weapon within a short period of time. Given the legal ability of a party to the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) to acquire enrichment and reprocessing facilities, produce weapon-usable materials and then withdraw from the Treaty after giving notice of its withdrawal three months in advance, a state would be free to develop nuclear weapons without, strictly speaking, violating the NPT.
McGoldrick, Fred, with contributions by Matthew Bunn, Martin Malin, and William H. Tobey. "Limiting Transfers of Enrichment and Reprocessing Technology: Issues, Constraints, Options." Project on Managing the Atom, Belfer Center for Science and International Affairs, Harvard Kennedy School, May 2011.