1. North Korea is believed to have exploded plutonium devices in its first two nuclear tests, in 2006 and 2009.

2. Iran will also halt work at its plutonium reactor and provide access to nuclear inspectors.

3. The site has also produced plutonium for NASA to use in space exploration and uranium for electricity production.

4. It disabled a heavy water plant that would have produced plutonium usable in a weapon.

5. The plutonium finishing plant is among the most badly contaminated buildings in the nation.

6. The plutonium is for generating electricity but has raised proliferation concerns.

7. Tehran also is only a few years away from completing a reactor that will produce plutonium, another pathway to nuclear arms.