Seymour Deitchman, a national security consultant who served with the IDA for over 28 years, said, "To the extent of my personal knowledge, the talk of using nuclear weapons in that war stopped after the JASON report on the subject." Gordon J. F. MacDonald, executive vice president of IDA at the time, reflected on the JASON report in 1998. MacDonald said that the "grim picture" painted in the report had a major effect on both Johnson and McNamara. It was central to McNamara's differences with the Joint Chiefs of Staff, who were sanguine about the nuclear option; this ultimately led to McNamara's resignation. RAND experts also conceded the report's credibility.