On January 4, 2021, Iran announced that it had begun enriching uranium to a level of 20 percent at a well-protected facility in Fordow. This level of enrichment departs completely from Iran’s commitment stipulated in the agreement reached with the world powers in 2015 (JCPOA). There are two main possible reasons for this Iranian announcement. One, it is intended as a provocation, designed to exert pressure on the world powers to lift the sanctions imposed on Iran, which were renewed by the United States. Two, Iran intends to accumulate uranium enriched at a level and quantity that will reduce the breakout time that Iran needs from the moment it decides to produce a nuclear explosive device. For 12 years Iran has been at a breakout range of between several months to two years, and has not yet taken the decision to break out to the bomb. This article analyzes the processes that Iran must go through from a breakout decision until it attains a nuclear weapon, and highlights the need to examine assumptions for calculating breakout times.