Obama was in France on Thursday to meet with the leaders of the world's top industrial nations at the Group of Eight summit. The two-day summit comes on the heels of the president's speech at London's Westminster Hall.
The United States says its missile defense plans are aimed at countering emerging threats from countries including Iran and North Korea, but Russia views the moves as possible encroachment.
For his part Russian President Dmitry Medvedev said the future of missile defense would be solved by future politicians - perhaps in the year 2020 - but that he and Obama can help lay the foundation now.
The world leaders are also expected to discuss ways to support the democratic transitions in Tunisia and Egypt and how to encourage other countries to pursue greater political freedoms.
Obama will meet personally with France's president and Japan's prime minister.
The G-8 comprises the U.S., Britain, France, Germany, Italy, Canada, Russia and Japan. The European Union is also represented.
The Associated Press contributed to this story.