In 2009, American President Obama delivered a speech in Prague in which he called nuclear terrorism one of the greatest threats to international security. With that in mind, Mr Obama hosted the first Nuclear Security Summit (NSS) in Washington DC in 2010, in order to draw attention, at the highest possible level, to the need to secure nuclear material and thus prevent nuclear terrorism. Forty-seven countries and three international organisations participated in the first summit. In 2012 the second NSS was held in Seoul. Fifty-three countries and four international organisations were invited. The first summit was concerned with making political agreements, while the follow-up in Seoul focused on the progress made on implementing those agreements. The third NSS, in The Hague in 2014, will centre on the results achieved and the future.