CNN: Iran has strengthened protections around enriched uranium stockpile Iran has significantly increased efforts in recent weeks to secure its stockpile of highly enriched uranium, according to a CNN report citing five sources familiar with US intelligence assessments. The report said Tehran has isolated parts of the stockpile and taken additional measures to restrict access to facilities where the material is believed to be stored. According to the report, Iran has filled in tunnels and rigged some entrances with explosive mines, making access to the uranium stockpile “much more difficult, dangerous, and time-consuming” than it was a month ago.