President Obama is citing significant, meaningful progress in securing nuclear materials around the world.

At the end of a global nuclear security summit, Obama also cited progress in efforts to keep nuclear devices out of the hands of terror groups. He said that includes crackdowns on "nuclear smuggling." Obama noted that the work goes on and is "by no means finished." He also praised the Iran nuclear deal.

The President said he is heartened that U.S. and Russian nuclear arsenals are on track to reach the lowest levels in six decades.

Russia declined an invitation to take part in the summit. More than 50 nations were represented at the two-day summit in Washington, DC.

In an earlier announcement, Obama said 102 nations ratified a treaty on the protection of nuclear material. (Metro Networks Inc.)