World leaders gathered in the US capital have agreed to take steps to prevent nuclear terrorism, which they saw is one of the most challenging threats to global security.

In a final declaration the 47 nations at the security summit in Washington issued a call to secure all vulnerable nuclear material in four years.

Some bilateral agreements on the sidelines were also announced - among them a deal signed by Russia and the US to destroy tonnes of weapons-grade plutonium.

Al Jazeera's Patty Culhane reports.

Source: Al Jazeera