Intelligence Agencies Minister Dan Meridor said Tuesday that the United States understands that Iran cannot be allowed to proliferate nuclear weapons despite sanctions against it, as was the case with North Korea.“Prevention is the policy of Washington,” he said.Earlier Tuesday, Obama discussed the risks of unsecured nuclear materials.“These dangerous materials are still vulnerable in too many places,” he said. “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.”Six world powers are expected to renew efforts next month to talk Tehran into curbing its uranium enrichment, which can yield fuel for atomic warheads as well as for civilian projects.Iran denies having any hostile designs.Strategic Affairs Minister Moshe Ya’alon said the mid- April talks would show “if there is a chance that the sanctions are working or that the Iranians are continuing to maneuver and advance toward a military nuclear capability.”But when asked during an interview with Army Radio if this meant that Prime Minister Binyamin Netanyahu’s government might be just weeks away from launching a war against Iran, Ya’alon demurred.“No. Look, we have to see,” he said. “The [Iranian nuclear] project is not static – whether that means progress, or sometimes, retreat. All sorts of things are happening there.”“Sometimes there are explosions there, sometimes there are worms, viruses, all kinds of things like that,” Ya’alon said, suggesting that setbacks plaguing Iran over the past three years, including the assassination of several of its scientists and the Stuxnet malware that stymied core computer systems, could be repeated.Obama, who inaugurated the first nuclear security summit in Washington in 2010, warned against “complacency” in preventing loose nuclear material from getting into the hands of terrorist groups.The legacy of the Soviet Union’s breakup, inadequate atomic stockpile controls and the proliferation of nuclear-fuel technology mean the world has lost precise count of atomic material, which could be used to make a weapon.There are at least 2 million kilograms of stockpiled weapons-grade nuclear material left over from decommissioned bombs and atomic-fuel plants, according to the International Panel on Fissile Materials, a New Jersey-based nonprofit research institute that tracks nuclear material. That is enough to make at least 100,000 new nuclear weapons – on top of the 20,000 bombs already in weapon states’ stockpiles.Because a terrorist needs only about 25 kilograms of highlyenriched uranium or eight kilograms of plutonium to improvise a bomb, the margin of error when it comes to accounting for the material is small.“The threat remains,” Obama said. “That’s why what’s required continues to be a serious and sustained effort.”Reuters contributed to this report.Meridor was speaking with Israel Radio from Seoul, where he is representing Israel at the Nuclear Security Summit.The main theme of the summit is preventing nuclear weapons from falling into the hands of what US President Barack Obama called “bad actors.” The Iranian nuclear issue has also been at the center of discussions on the sidelines of the conference.Meridor spoke with Israel Radio following a meeting with the US president.“The line that Obama draws is clear – both with North Korea and with Iran,” he said, but declined to discuss what was said behind closed doors.The US, he added, would attempt to convince Russia to add on to the pressure already being applied to Iran, including the current implementation of international sanctions.