Barack Obama, the US president, has said that the threat of nuclear weapons remains a potent challenge for the globe to confront, telling foreign leaders that "the security of the world depends on the actions that we take".
Speaking at a two-day nuclear security summit in South Korea's capital Seoul on Tuesday, Obama said that the international community had made progress in removing nuclear materials and improving security at nuclear facilities around the globe.
As a result, he said, more of the world's nuclear materials will not fall into the hands of terrorists.
But he said "there are still too many bad actors in search of these dangerous materials and these dangerous materials are still vulnerable in too many places".
"It would not take much, just a handful or so of these materials, to kill hundreds of thousands of innocent people, and that's not an exaggeration, that's the reality that we face. "
- Barack Obama, US President
"It would not take much, just a handful or so of these materials, to kill hundreds of thousands of innocent people, and that's not an exaggeration, that's the reality that we face," Obama said on the concluding day of the summit attended by nearly 53 world leaders.
While the official agenda of the summit is to strengthen measures to track the movement of nuclear materials worldwide, much of the dialogue focussed on efforts to get North Korea to back off a planned rocket launch slated for next month and return to disarmament talks.
North Korea announced earlier this month that it would send a satellite into space aboard a long-range rocket.
Pyongyang has said the launch is part of its peaceful space programme and says a new southern flight path is meant to avoid other countries. Previous rockets have been fired over Japan.
Last week Naoki Tanaka, the Japanese defence minister, said his country could shoot down the rocket if it entered its airspace.
Even, China, a close ally of the isolated communist nation, has voiced its concern over the North's launch plan.
On Monday, a senior US official said that Hu Jintao, the Chinese president, expressed "serious concern" about North's plan during a meeting with Obama on the sidelines of the summit.
Warning to North Korea
Obama has urged North Korean leaders to abandon their rocket plan or risk jeopardising their country's future and thwarting a recent US pledge of food aid in return for nuclear and missile test moratoria, considered a breakthrough after years of deadlock.
On Monday while speaking at a university in Seoul, Obama said that he was pushing for "a world without nuclear weapons".
The US President held out the prospect of new reductions in the US arsenal as he sought to rally world leaders for additional concrete steps against the threat of nuclear terrorism.
"We can already say with confidence that we have more nuclear weapons than we need," Obama told students at South Korea's Hankuk University before the summit.
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Obama told students that he was confident the US and Russia could jointly reduce their stockpiles of nuclear weapons, building on the successful extension of arms control agreements known as START.
Obama also seemed anxious to deal with Iran on a more immediate timeline.
"There is time to solve this diplomatically. It is always my preference to solve these issues diplomatically," he said.
"Iran's leaders must understand that there is no escaping the choice before it. Iran must act with the seriousness and sense of urgency that this moment demands," Obama said. "Iran must meet its obligations."
Iran insists there is no military element to its programme, but Western powers fear it is constructing nuclear weapons.
Neither Iran nor North Korea is participating in the summit.
Source: Al Jazeera and agencies