Obama warns Russia of biting economic sanctions

US President Barack Obama Tuesday expressed concern over further encroachment of Russia in Ukraine and warned Russia of additional sanctions if Russia takes this step. "It is up to Russia to act responsibility, if it fails there will be additional costs -- it will have greater effect on Russian economy," he told a press conference at the end of the two-day Nuclear Security Summit the Hague."We are prepared to resolve this diplomatically but prepared to take further steps if necessary," he stressed.Obama noted that the West till now has put Russian individuals on the blacklist but if the situation deteriorates, trade and arms sanctions would be imposed which will hurt Russia badly.The US President said the Russian annexation of Crimea "is not a done deal" as the international community is not recognizing it. He said that like Syria, Russia has never been more isolated internationally. On his part, Dutch Prime Minister Mark Rutte told the joint press conference that the EU and US are working very closely together on Ukraine. He said that sanctions will be designed in such a way that they will have a very big impact on Russia's economy and less on other countries.Turning to the NSS, Obama said it was a big success in gearing international support to confront "one of the biggest threat to world security, nuclear terrorism." He noted that 12 countries and dozens of organizations have agreed to rid themselves of highly enriched uranium and plutonium. The NSS in The Hague drew to a close on Tuesday afternoon with the publication of the final communique. The communiqu{ states that the 58 world leaders who took part made concrete agreements to stop terrorists getting their hands on nuclear material which further reduces the threat of a nuclear attack. Later this evening Obama will fly to Brussels for a summit with EU leaders tomorrow.