World leaders gathered in the US capital have agreed to take steps to prevent "nuclear terrorism", which they said is one of the biggest threats to global security.<br /><br />In a final declaration the 47 nations at the security summit in Washington DC issued a call to secure all vulnerable nuclear material within four years.<br /><br />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.<br /><br />Al Jazeera's Patty Culhane reports. (Apr 14, 2010)
