Iran has announced it will hold military exercises to boost protection of its nuclear sites.
A military statement said drills would be held in southern Iran to counter all possible threats, especially to public, important and nuclear centres.
Speculation has been increasing that Israel may launch a military strike on Iran's nuclear facilities, reports the BBC.
The latest move comes as United Nations nuclear experts begin a two-day visit to Iran, the second such trip in a month.
Late last year Iran conducted 10 days of military exercises near the Strait of Hormuz at the entrance to the Gulf, test-firing several missiles.