US President Barack Obama on Tuesday praised the 'tangible' progress achieved by world leaders at a summit on nuclear security in The Hague, dpa. A total of 35 countries signed up to global standards after two days of talks in the Dutch city, but Russia and Pakistan were among the most notable exceptions. 'This was not about vague commitments, it was about taking tangible and concrete steps to secure more of the world's dangerous nuclear material ... and that's what we've done,' Obama said after the two-day Nuclear Security Summit (NSS). German Chancellor Angela Merkel was less upbeat, however, saying a lack of progress in certain areas left 'much to be desired.' She also warned that four years of work had not eliminated the risk of terrorists building a so-called dirty bomb, combining conventional explosives with nuclear material. Leaders from 53 countries gathered Monday and Tuesday in The Hague to address widespread fears that nuclear materials - including those used in medical, research and energy facilities - could fall into the wrong hands. The 35 countries pledged to incorporate International Atomic Energy Agency (IAEA) guidelines on nuclear security into their national law.
