World leaders have begun arriving in Washington for an unprecedented summit to secure nuclear stockpiles and keep weapons material out of the hands of terrorists.
The White House says US president Barack Obama has called the 47-nation conference to tackle what it describes as the most dangerous threat to the world – nuclear security.
A massive security blanket has been thrown over a large part of Washington for the biggest gathering of world leaders on US soil since the end of World War II.
Mr Obama wants the assembled presidents and prime ministers to agree to secure all nuclear materials within four years and is also likely to call for tougher prosecutions of traffickers in weapons grade materials.
“We know that organisations like Al Qaeda are in the process of trying to secure nuclear weapons or other weapons of mass destruction, and would have no compunction at using them,” Mr Obama said.
The president will also have a series of meetings on the sidelines of the summit, aimed in part at trying to win support for new sanctions against Iran.
US secretary of state Hillary Clinton says the fear of a nuclear war between superpowers has waned, but has been replaced by the threat of nuclear-armed terrorists.
“We know that terrorist groups, primarily Al Qaeda, persist in their efforts to obtain enough nuclear material to try to do something that would cause such mass havoc and terror and damage and destruction, that it would be devastating,” she said.
The summit comes a week after the US signed a new arms control treaty with Russia and unveiled a new policy about the use of nuclear weapons.
But this meeting will focus on separated plutonium and highly enriched uranium.
“There’s a lot of nuclear material that is not as secure, that hasn’t been destroyed,” Senator Clinton said.
“It isn’t under lock and key in many places in the world. Particularly in the former Soviet Union, but not exclusively there.”
Joseph Cirincione, the president of the Ploughshares Fund – an American foundation focused on nuclear weapons policy and conflict resolution – says Mr Obama will have his work cut out for him.
“India and Pakistan don’t really agree that the number one task is to secure their nuclear materials,” he said.
“They’re part of the crowd you want to convince.”
Although the summit does not officially start until tomorrow, Mr Obama has already begun a series of one-on-one meetings with several leaders, including those of India and Pakistan.
He is also hoping to use a meeting tomorrow with China’s president Hu Jintao to win support for new sanctions against Iran.
Meanwhile, US defence secretary Robert Gates says Iran is not a nuclear-capable country at the moment, nor does he think it inevitable that Iran will become one.
“We have not … drawn that conclusion at all. And in fact, we’re doing everything we can to try and keep Iran from developing nuclear weapons,” he said.
Some world leaders will not be at the summit, including Israeli prime minister Benjamin Netanyahu, who is sending his deputy instead.
Senator Clinton denies that is a snub, saying a number of nations are not sending their heads of government.
“Gordon Brown is not coming from Great Britain, Kevin Rudd is not coming from Australia, King Abdullah is not coming from Saudi Arabia,” she said.
Defence Minister John Faulkner will represent Australia.