U.S. and Israeli intelligence officials have determined that Iran does not yet have "break out" capability
According to U.S. and Israeli intelligence officials, and independent assessments by the Institute for Science and International Security, it would currently take Iran at least four months to produce sufficient weapons-grade uranium (WGU) for a single nuclear bomb, and at least a year total to produce a crude testable nuclear device, once Iran’s Supreme Leader Ayatollah Ali Khamanei decides to do so. It would take several more years to develop a miniaturized nuclear warhead for a missile.
Although Iran is clearly positioning itself to develop a nuclear weapons capability, James Clapper, the Director of National Intelligence, has testified that there is no hard evidence that Khamenei has yet made the final decision to translate those capabilities into a bomb. Moreover, Khamanei is unlikely to dash for a weapon anytime soon because doing so would require Iran to divert low-enriched uranium (LEU) stockpiles and enrich to weapons-grade level at the declared enrichment facilities at Natanz or Fordow. Because International Atomic Energy Agency (IAEA) inspectors would detect such moves, the Iranian regime is unlikely to “break out” until they can dramatically reduce the timeline to build several bombs or build a weapon at new covert facilities. This could be years away.