Between 2003 and 2005, the Iranians refrained from any nuclear activity under the influence of the impression created by America’s pre-emptive policies in the region, which served as the main instrument that enabled the Europeans to force Iran to postpone uranium conversion and enrichment. But when the Iranians realized in 2005 that there was no actual threat behind their fears of U.S. pre-emption, they decided to start conversion and then enrichment.