Leaders of 53 nations and four international organizations have gathered in Seoul for a two-day summit on expanding and deepening international cooperation in thwarting nuclear terrorism.

The threat of nuclear terrorism loomed large following the 9/11 attacks on the United States. But global efforts to address it had remained low-key until U.S. President Barak Obama energized them.

In a speech in Prague in 2009, Obama presented his vision of a world free of nuclear weapons. One initiative he proposed at the time was a global summit on nuclear security to deal with the growing danger of nuclear terrorism.

Obama noted that while the threat of global nuclear war had decreased with the end of the Cold War, the risk of a nuclear attack had rather increased as the existing nuclear nonproliferation regime could not rein in malicious non-state actors. To curb the threat posed by terrorist groups, he pledged to secure all vulnerable nuclear material around the world within four years.

Obama hosted the first Nuclear Security Summit in Washington in 2010. The inaugural meeting adopted a communiqu and a work plan, setting out 50 cooperative tasks in 11 fields. Each participating state was expected to carry them out on a voluntary basis.

The Seoul summit is the second meeting aimed primarily at reviewing and assessing the progress that participating states have made since the Washington conference. During the two years, significant progress has been made. For instance, several countries have eliminated their stockpiles of highly enriched uranium.

Yet the nuclear terrorism threat has not noticeably abated. For one thing, large amounts of HEU and separated plutonium still remain unsecured. Experts estimate that some 1,600 tons of HEU and 500 tons of plutonium are scattered around the world. This volume is large enough to produce some 126,000 nuclear weapons.

Hence the Seoul meeting will encourage participating states to ratchet up their commitment to eliminating or reducing fissile material stockpiles. Leaders attending the summit need to make bold and specific commitments to realize the vision of a world without nuclear weapons.

As with the Washington conference, the Seoul summit will focus on the three key dimensions of nuclear security ― response to terrorism, protection of nuclear material and facilities, and prevention of illicit trade in nuclear material.

Yet it needs to expand the scope of discussions to deal with issues that were not covered in the inaugural summit. One such issue concerns radiological terrorism.

The destructive impact of radiological terrorism is much weaker than that of nuclear terrorism. Yet the threat of radiological terrorism warrants more attention as terrorist groups can easily obtain the materials needed for so-called “dirty bombs” by combining them with conventional explosives.

Japan’s nuclear catastrophe a year ago has made it necessary to discuss nuclear security together with nuclear safety. Nuclear security is about preventing intentional terrorist attacks, while nuclear safety focuses on preventing natural disasters and unintended human errors.

But a terrorist attack on a nuclear power plant could create a situation not much different from that caused by a safety lapse or a natural disaster. Both incidents also require similar response measures. Hence it is necessary to discuss the ways in which efforts in both areas can reinforce each other.

It is worth noting that Korea, as host of the important global security forum, intends to make contributions of its own by sharing its state-of-the-art technologies with participating states.

One important task in securing vulnerable nuclear material concerns the conversion of research reactors from high-enriched to low-enriched uranium fuel. Korea is the only country in the world to develop high-density low-enriched uranium powder that can replace HEU as fuel for research reactors. This technology can help participating states minimize their use of HEU.

Korea has also developed a radiological material monitoring technology that can track radioactive sources in real time using GPS. This technology can significantly enhance accounting capabilities.

The Seoul summit carries great meaning for Korea in many ways. For instance, it can be seen as global recognition of the high standards Korea has maintained in nuclear nonproliferation, security and safety.

The summit also reflects Korea’s elevated standing in the international arena. In 2010, Korea hosted the G20 summit, establishing itself as a major participant in global discussions on economic and financial cooperation. The nuclear summit in Seoul will help Korea play leadership role in international security discussions. We hope the Seoul summit bears ample fruit.