2012 Seoul Nuclear Security Summit begins morning plenary session Leaders and representatives attend the morning plenary session of the 20...

2012 Seoul Nuclear Security Summit begins morning plenary session

Leaders and representatives attend the morning plenary session of the 2012 Seoul Nuclear Security Summit in Seoul, capital of the Republic of Korea (ROK), March 27, 2012. (Xinhua/Li Xueren)

Video grab taken on March 27, 2012 shows the meeting hall of the morning plenary session of the Nuclear Security Summit (NSS) in Seoul, South Korea. The morning plenary session of the 2012 Seoul Nuclear Security Summit started here Tuesday morning. (Xinhua)

Video grab taken on March 27, 2012 shows South Korea's President Lee Myung-bak (R) speaks at the morning plenary session of the Nuclear Security Summit (NSS) in Seoul, South Korea. (Xinhua)

SEOUL, March 27 (Xinhua) -- The morning plenary session of the 2012 Seoul Nuclear Security Summit started here Tuesday morning.

Giving an opening remark at the beginning of the session, South Korean President Lee Myung-bak said it is the obligation of world leaders to maintain peace and security of all mankind. Therefore, they must carry out all means to prevent terrorists from obtaining nuclear materials.

President of the United States Barack Obama said more nations come to the summit "not to talk but to take actions", adding that international cooperation is needed to combat nuclear terrorism.

Leaders and representatives from more than 50 nations and four international institutions gathered here to discuss the response to nuclear terrorism, protection of nuclear materials and facilities as well as prevention of illegal trafficking of nuclear materials.

The Seoul communique, to be announced on Tuesday, is expected to reaffirm the international commitments to minimizing the use of highly-enriched uranium and plutonium and expand discussions on nuclear safety in the context of nuclear security following the nuclear crisis in Japan.