Washington: Prime Minister Narendra Modi on Friday said the Brussels attacks have illustrated how real and immediate is the threat to nuclear security from terrorism and the world needs to drop the notion that terrorism is someone else's problem and that "his" terrorist is not "my" terrorist. In a strong statement during his intervention on nuclear terrorism threat at the Fourth Nuclear Security Summit (NSS) here, Modi said that while terrorism is globally networked, "but we still act only nationally to counter this threat". "Drop the notion that terrorism is someone else's problem and that 'his' terrorist is not 'my' terrorist. Nuclear security must remain an abiding national priority. All States must completely abide by their international obligations." Seated next to US President Barack Obama during the NSS dinner, Modi said Obama has done a great service to global security by putting the spotlight on nuclear security. "Brussels shows us how real and immediate is the threat to nuclear security from terrorism," he said, referring to the March 22 terror attacks in the Belgian capital that killed 35 people and left over 200 injured. He said the world needs to focus on three contemporary features of terrorism. "First, today's terrorism uses extreme violence as theatre. Second, we are no longer looking for a man in a cave, but we are hunting for a terrorist in a city with a computer or a smart phone. Third, state actors working with nuclear traffickers and terrorists present the greatest risk." "Terror has evolved. Terrorists are using 21st century technology. But our responses are rooted in the past. Terrorism is globally networked. But, we still act only nationally to counter this threat. The reach and supply chains of terrorism are global; but genuine cooperation between nation states is not," Modi said. "Without prevention and prosecution of acts of terrorism there is no deterrence against nuclear terrorism." Modi urged the nations to keep alive the push for nuclear security that was begun by Obama during his presidency. "This legacy of President Obama must endure," said Modi. This was the fourth and final NSS of Obama's presidency. With Obama, who conceived and championed the meetings, leaving office next year, this is likely to be the last such summit. Leaders of 53 nations and four international organisations are attending the Washington summit on nuclear security. The NSS process has focused on the global threat posed by nuclear terrorism and urgent measures required to prevent terrorists and other non-state actors from gaining access to sensitive nuclear materials and technologies. The 2016 Summit is expected to take stock of the progress of the previous NSS Communiques and work plan and outline the future agenda.