All countries can – and must – do more to secure nuclear materials. And countries must take action today, not the day after terrorists explode a nuclear device in a major city.

Or as Sam Nunn, former Senator and Co-Chairman of the Nuclear Threat Initiative (NTI), has said [2], “As citizens and leaders, we need to ask ourselves this question: If we had a catastrophic nuclear terrorist attack on Moscow or New York, on Tokyo or Tel Aviv, or on any other city in the world, what steps would we wish we had taken to prevent it?”

In a little more than two months, world leaders will come together in Seoul, South Korea to discuss this pressing question. The goal of the 2012 Nuclear Security Summit is to build on the success and momentum of the 2010 Nuclear Security Summit, which brought together leaders from 47 countries in Washington, DC to develop concrete steps to reduce the nuclear threat. At the 2010that Summit, leaders exchanged ideas – and made commitments – to secure loose nuclear materials and prevent terrorist groups – and other rogue actors – from acquiring nuclear weapons.

The Nuclear Security Summit in Seoul will be a critical opportunity for countries to check in on the progress that they have made in fulfilling commitments pledged at the 2010 summit [3].

The recently released NTI Nuclear Materials Security Index: Building a Framework for Assurance, Accountability and Action (PDF [4]) suggests that despite important progress in recent years – including increased political awareness about the threat – many countries are still struggling to secure the dangerous materials that can be used to build nuclear weapons.

The NTI index [5] provides a first-of-its-kind, public baseline assessment of the status of nuclear material security conditions in 176 countries, with a special focus on the 32 countries with one kilogram or more of weapons-usable nuclear materials. NTI teamed up with the Economist Intelligence Unite (EIU) to evaluate and rank countries based on five categories: Quantities and Sites, Security and Control Measures, Global Norms, Domestic Commitment sand Capacity, and Societal Factors.

Australia earned the top score for nuclear security, while the United States ranks 13th. Iran, Pakistan and North Korea received the lowest marks for securing nuclear materials. “This is not about congratulating some countries and chastising others,” Nunn said. “We are highlighting the universal responsibility of states to secure the world’s most dangerous materials.”

As part of its report, NTI recommended concrete steps to build the foundation for a global system to secure, monitor and control nuclear materials. These recommendations – along with similar recommendations from the Fissile Materials Working Group [6], a coalition of more than 60 U.S. and international experts dedicated to securing vulnerable fissile materials – provide a roadmap for policymakers worldwide to reduce the threat of nuclear terrorism.

“We know that to get the materials they need, terrorists will go where the material is most vulnerable,” said Senator Sam Nunn. “Global nuclear security is only as strong as the weakest link in the chain.”