With the terror attacks in Brussels still fresh in the memories of arms controllers, a global summit, the last of four held at the urging of President Barack Obama, will take place in Washington, D.C., on March 31 and April 1. Its focus is on preventing nuclear material from falling into the wrong hands. The questions of “what if” or worse, “when and how?” have again been raised after the Belgian massacres and the reports that jihadists had been surveilling a nuclear expert in Belgium who could have become a target of kidnapping or other threatening action.

Leaders of 47 countries are expected to attend the Nuclear Security Summit, but President Vladimir Putin of Russia, a major nuclear power, will be absent. A Russian Foreign Ministry spokeswoman, Maria Zakharova, said in early January that there was nothing left to discuss. “The political agenda of these meetings has been exhausted,” she said, according to a Russian news report. Russia did attend the three pervious summits, in 2010 in Washington, 2012 in Seoul and 2014 in The Hague, and there have been suggestions that Putin’s absence may be related more to recent Russian actions in Ukraine and Syria.

The Washington summit will not be dealing with nuclear waste material from military sites, where 85 percent of radioactive material is thought to exist. Countries are reluctant to divulge or to even discuss what they consider to be security issues surrounding those sources of spent fuel. In the current sessions, only the disposal of spent fuel from civilian nuclear power plants is on the table, though the military dimension of the problem hovers over discussions.

Unlike non-nuclear power plants — fueled, for example, by coal, a producer of “dirty” discharges into the atmosphere — the residue of nuclear reactors contains uranium and plutonium. The question has been whether this nuclear-laced waste should be buried or otherwise contained, or instead reprocessed to remove extraneous material and to recycle the plutonium and uranium for reuse.

But for what reuse? The concern has been that reprocessed and recycled nuclear material, plutonium in particular, which forms the larger part of the waste, will go into expanding nuclear weapons programs or be siphoned off illegally and either sold to would-be nuclear powers or acquired even in small quantities by terrorist organizations.

As background to the final nuclear summit of the Obama administration, the Carnegie Corporation of New York has produced an interactive web page entered through a short, dramatic video, “The Greatest Threat: Nuclear Terrorism in an Age of Vulnerability,” which links to a comprehensive package of expert information covering many aspects of the dangers present in the tons of nuclear material stored around the world and what some counties have done to defuse the threat and how others may be exacerbating it.

“Throughout the world, stockpiles of uranium and plutonium, as well as other radioactive materials, are stored in facilities that have not received the level of scrutiny warranted by the potentially devastating implications of a security failure,” the Carnegie Corporation says in introducing its interactive site on the issue.

In a teleconference briefing before the summit from the Asia Society in Washington, Gary Samore, the executive director for research at the Belfer Center for Science and International Affairs at Harvard University and the former White House coordinator for arms control and weapons of mass destruction under President Obama, said that the rapid growth of civilian nuclear power and the intention in some countries to build expensive reprocessing facilities would be issues up for discussion.

Asian countries are major players in the reprocessing debate. The US wants to discourage the building of more reprocessing plants, which it will argue do not make economic sense, apart from producing radioactive fissile materials that can pose global threats.

Asian countries have attended the cycle of summits on nuclear security, Samore said, although with different degrees of positive cooperation in confronting potential dangers inherent in reprocessing and production of bomb-grade nuclear material. He said that China has been “surprisingly cooperative” in discussions because of its desire for international assistance in expanding nuclear energy. South Korea and Japan have been most active in addressing how to prevent the spread of nuclear material from civil power plants. The case of North Korea, a perennial outlier, will be discussed “off the agenda” at the summit, Samore said.

He pointed to South Asia, India and Pakistan having been the least cooperative in talks about spent nuclear fuel. He described India’s security record in protecting nuclear materials as “sloppy,” but added that the US has been able to discuss the issue of nuclear waste from civilian sites with Pakistan. Samore also pointed to the obvious reason for heightened concern about South Asia: terrorism in the region.

Running parallel to the formal nuclear security talks involving governments will be the Nuclear Industry Summit 2016, from March 30-31 in Washington, where numerous private-sector companies and government research centers will take part in talks and view exhibitions of developments in the nuclear protection field. A nongovernment organization conference will also be taking place on the margins of the government meetings. Both industry and NGO activists plan to present their ideas to the summit and the public.

Barbara Crossette

Barbara Crossette is the senior consulting editor and writer for PassBlue and the United Nations correspondent for The Nation. She is also a member of the Council on Foreign Relations. She has also contributed to the Oxford Handbook on the United Nations.

Previously, Crossette was the UN bureau chief for The New York Times from 1994 to 2001 and previously its chief correspondent in Southeast Asia and South Asia. She is the author of “So Close to Heaven: The Vanishing Buddhist Kingdoms of the Himalayas,” “The Great Hill Stations of Asia” and a Foreign Policy Association study, “India Changes Course,” in the Foreign Policy Association’s “Great Decisions 2015.”

Crossette won the George Polk award for her coverage in India of the assassination of Rajiv Gandhi in 1991 and the 2010 Shorenstein Prize for her writing on Asia.