The book describes how the agency sent a Russian nuclear scientist — who had defected to the United States and was secretly working for the C.I.A. — to Vienna in February 2000 to give plans for a nuclear bomb triggering device to an Iranian official under the pretext that he would provide further assistance in exchange for money. The C.I.A. had hidden a technical flaw in the designs.

The scientist immediately spotted the flaw, Mr. Risen reported. Nevertheless, the agency proceeded with the operation, so the scientist decided on his own to alert the Iranians that there was a problem in the designs, thinking they would not take him seriously otherwise.

Mr. Risen described the operation as reckless, arguing that Iranian scientists may have been able to “extract valuable information from the blueprints while ignoring the flaws.” He also wrote that a C.I.A. case officer, believing that the agency had “assisted the Iranians in joining the nuclear club,” told a Congressional intelligence committee about the problems, but that no action was taken.

It is not clear whether the Iranians had figured out that the Russian scientist had been working for the C.I.A. before publication of Mr. Risen’s book.

The Bush administration had sought Mr. Risen’s cooperation in identifying his sources for the Iran chapter of his book, and it obtained an earlier subpoena against him in January 2008 under Attorney General Michael B. Mukasey. But Mr. Risen fought the subpoena, and never had to testify before it expired last summer. That left it up to Mr. Holder to decide whether to press forward with the matter by seeking a new subpoena.

If a judge does not agree to quash the subpoena and Mr. Risen still refuses to comply, he risks being held in contempt of court. In 2005, a Times reporter, Judith Miller, was jailed for 85 days for refusing to testify in connection with the Valerie Plame Wilson leak case.

Department rules say prosecutors may seek such subpoenas only if the information they are seeking is essential and cannot be obtained another way, and the attorney general must personally sign off after balancing the public’s interest in the news against the public’s interest in effective law enforcement.

Congress is considering legislation that would let judges make that determination, giving them greater power to quash subpoenas to reporters. The Obama administration supports such a media-shield bill, and the House of Representatives has passed a version of it. But a Senate version has been stalled for months.