The new national intelligence estimate, or NIE, says Tehran likely has resumed work on nuclear-weapons research in addition to expanding its program to enrich uranium—updating a contested 2007 estimate that concluded the arms program had all but halted in 2003.

But it doesn’t conclude that Iran has relaunched a full-blown program to try to build bombs. According to the assessment, Iran’s debate over whether to do so suggests international sanctions may be causing divisions in Tehran, U.S. officials said…

The NIE’s findings suggest that, in the U.S. view, at least some Iranian leaders are worried that economic turmoil fueled in part by international sanctions could spur opposition to the regime—though officials acknowledge it is impossible for outsiders to determine the precise effect of sanctions on decision-making in Tehran.