Heads of state from 53 countries were gathering in The Hague on Monday for the third Nuclear Security Summit (NSS), although the meeting looked likely to be overshadowed by emergency Group of Seven (G7) talks on the Crimean crisis, dpa reported. The two-day summit on nuclear terrorism - the largest ever held in the Netherlands - is aimed at "making the world a bit safer," Dutch Prime Minister Mark Rutte said, adding that the issue was one of the greatest dangers facing humanity. The first NSS took place in Washington in 2010, an initiative of U.S. President Barack Obama, and a second took place in Seoul two years later.