The nation’s ability to identify the source of a nuclear weapon used in a terrorist attack is fragile and eroding, according to a report released Thursday by the National Research Council.

Such specialized detective work, known as nuclear attribution, seeks to study clues from fallout and radioactive debris as a way to throw light on the identity of the attacker and the maker of the weapon. In recent years, federal officials have sought to improve such analytic skills, arguing that nuclear terrorism is a long-term threat.

The major goals of the federal efforts are to clarify options for retaliation and to deter terrorists by letting them know that nuclear devices have fingerprints that atomic specialists can find and trace.

The report, "Nuclear Forensics: A Capability at Risk," was made public by the National Research Council, the research arm of the National Academy of Sciences. It summarizes a secret version completed in January. Three federal agencies—the Department of Homeland Security, the Defense Department and the National Nuclear Security Administration, which is part of the Energy Department—requested the study.

The public report says that a series of factors threaten to undermine the nation’s ability to conduct nuclear investigations intended to learn the provenance of an explosive device, whether it is a true atomic weapon or a so-called dirty bomb that uses conventional explosives to spew radioactivity.

"Although U.S. nuclear forensics capabilities are substantial and can be improved, right now they are fragile, underresourced and, in some respects, deteriorating," the report warns. "Without strong leadership, careful planning and additional funds, these capabilities will decline."

Much of the forensic expertise is in the laboratories that maintain the nation’s nuclear arsenal. They had their heyday during the Cold War and are now struggling to attract personnel, finance projects and carve out new identities.

The study was done by a dozen nuclear specialists from academia, industry, the military and the nuclear laboratories, including Los Alamos National Laboratory and Lawrence Livermore National Laboratory. It was led by Albert Carnesale, a nuclear engineer and chancellor emeritus of UCLA, who during the Cold War represented the United States in atomic negotiations.

The panel criticized the federal government’s management of the forensic endeavor, saying several agencies shared responsibility for investigations but did so "without central authority and with no consensus on strategic requirements to guide the program." The organizational complexity, the panel said, "hampers the program and could prove to be a major hindrance operationally."

In addition, the panel cited a lack of skilled personnel, the use of outdated instruments and the existence of old facilities in need of upgrading. For general support, the forensics work depends on the U.S. program for maintaining its nuclear arsenal, the report noted, adding, however, that its "funds are declining."

The report calls on the federal government to take steps to strengthen its forensic capabilities. It argues for the necessity of better planning, more robust budgets, clearer lines of authority and more realistic exercises.

In a preface to the report, Carnesale noted that the federal government had worked hard to improve the situation since the classified version of the report was issued in January, and that it had appeared to make progress.

"Much work," he added, "remains to be done."

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