U.S. President Barack Obama issued a stern message direct to North Korea as he prepared to join other world leaders for a nuclear security summit in Seoul. Speaking at Seoul University ahead of the event Obama said Pyongyang's provocation and pursuit of atomic weapons had undermined security. 　　Barack Obama: "Today we say, Pyongyang, have the courage to pursue peace and give a better life to the people of North Korea." Obama also said there could yet be a diplomatic solution to the row over Iran's suspected development of weapons, which it denies. But he warned the clock is ticking. 　　Barack Obama: "Today I will meet with the leaders of Russia and China as we work to achieve a resolution in which Iran fulfills its obligations. There is time to solve this diplomatically. It is always my preference to solve these issues diplomatically. [4]But time is short." A massive security operation's underway around the summit venue where the leaders of more than 50 nations are meeting. 　　The two-day gathering is intended to focus on measures to protect nuclear materials and stop illicit trafficking. North Korea isn't attending and its nuclear programme is not on the agenda but its announcement of a long-range rocket launch in April is likely to take centre stage. (Paul Chapman/ Reuters)