Published: Mar 23, 2012 12:29 PM EDT
Updated: Mar 23, 2012 3:40 PM EDT

WASHINGTON (AP) - President Barack Obama heads to Seoul, South Korea, later today for an international summit on keeping nuclear weapons material out of the hands of terrorists.
 
Nearly 60 world leaders are expected to attend the gathering Monday and Tuesday.
 
Obama also plans to make a stop at the Demilitarized Zone separating North and South Korea and to visit some of the approximately 28,500 U.S. troops stationed in South Korea, as a legacy of the Korean war six decades ago.