But the U.S. policy of shielding the Israeli program has recently provoked new controversy, partly because of allegations that it played a role in the censure of a well-known national-laboratory arms researcher in July, after he published an article in which he acknowledged that Israel has nuclear arms. Some scholars and experts are also complaining that the government’s lack of candor is complicating its high-profile campaign to block the development of nuclear arms in Iran, as well as U.S.-led planning for a potential treaty prohibiting nuclear arms anywhere in the region.

The U.S. silence is largely unwavering, however. “We would never say flatly that Israel has nuclear weapons,” explained a former senior State Department official who dealt with nuclear issues during the Bush administration. “We would have to couch it in other language, we would have to say ‘we assume’ or ‘we presume that Israel has nuclear weapons,’ or ‘it’s reported’ that they have them,” the former official said, requesting that his name not be used due to the political sensitivity surrounding the topic.

President Barack Obama made clear that this four-decade-old U.S. policy would persist at his first White House press conference in 2009, when journalist Helen Thomas asked if he knew of any nations in the Middle East with nuclear arms. “With respect to nuclear weapons, you know, I don’t want to speculate,” Obama said, as though Israel’s established status as a nuclear-weapons state was only a matter of rumor and conjecture.

So wary is Paul Pillar, a former U.S. national-intelligence officer for the Middle East, of making any direct, public reference to Israel’s nuclear arsenal that when he wrote an article this month in The National Interest, entitled “Israel’s Widely Suspected Unmentionables,” he referred to warheads as “kumquats” throughout his manuscript.

Even Congress has been coy on the subject. When the Senate Foreign Relations Committee published a 2008 report titled “Chain Reaction: Avoiding a Nuclear Arms Race in the Middle East,” it included chapters on Saudi Arabia, Egypt, and Turkey—but not Israel. The 61-page report relegated Israel’s nuclear arms to a footnote that suggested that Israel’s arsenal was a “perception.”

“This report does not take a position on the existence of Israeli nuclear weapons,” the report said. “Although Israel has not officially acknowledged it possesses nuclear weapons, a widespread consensus exists in the region and among experts in the United States that Israel possesses a number of nuclear weapons. For Israel’s neighbors, this perception is more important than reality.”

While former White House or cabinet-level officers—such as Gates—have gotten away with more candor, the bureaucracy does not take honesty by junior officials lightly. James Doyle, a veteran nuclear analyst at Los Alamos National Laboratory who was recently censured, evidently left himself open to punishment by straying minutely from U.S. policy in a February 2013 article published by the British journal Survival.