Representatives from more than 50 countries, including U.S. President Obama, are in Seoul for the second round of the Nuclear Security Summit, officials said. The summit, set to officially begin Monday, is aimed at keeping nuclear materials out of the hands of terrorists, the Council on Foreign Relations reported. Although not many new commitments are expected to be made at the summit, \"its biggest value might be the fact that it has already created an incentive for leaders to deliver in advance,\" said Michael A. Levi, an expert on nuclear security. \"The Nuclear Security Summit series [a third meeting will be held in 2014 in the Netherlands] was initiated by President Obama as part of a broad effort to focus international attention on preventing nuclear terrorism, particularly by boosting security for nuclear materials,\" he said. Levi said he does not expect North Korea or Iran, countries thought to be developing nuclear weaponry, to be main talking points at the summit, but will likely come up outside the conference. \"Neither those two countries will be explicitly on the agenda. It\'s important to think about two things when you look at the connection between this summit and those challenges,\" he said. \"Nuclear materials that could be used in terrorist weapons remain in dozens of countries around the world and it\'s important for us to continue to improve security and lower the odds of a nuclear terrorist attack. One of the values of a series of summits like this is that it stops us from forgetting about this issue just because we happen to be more focused on the Iranian program or the North Korean program right now.\"