When one of your trio of ex-security chiefs goes public to undermine your declared assessments and strategies regarding Iran, you might reasonably challenge the credibility of his argument by claiming that he carries some kind of personal grudge against you, or is about to enter the political battlefield in a party other than yours.

When two of them do it, your questioning of their motives starts to look a little more wobbly. When all three weigh in, with varying degrees of stridency, it is the credibility of your positions, not theirs, that can start to become the issue.

Such is the case now that Yuval Diskin, the head of the internal intelligence Shin Bet agency until a year ago, has publicly savaged the handling of the Iranian nuclear threat by Prime Minister Benjamin Netanyahu and Defense Minister Ehud Barak.

Gabi Ashkenazi, the IDF chief of general staff until February of last year, is on record from as long ago as last summer as declaring that sanctions, rather than military intervention, represent the best means to thwart Iran’s nuclear program, while also stressing the need to keep “all the options on the table.” In his private dealings with the political leadership while in uniform, he is widely reported to have used language far more forceful than that mild formulation.

Ashkenazi’s comments have long since been eclipsed by ex-Mossad chief Meir Dagan’s repeated public declarations that military intervention at this stage would be an act of supreme foolishness. Time and again in the past year, Dagan has said that an Israeli strike might not significantly impact the Iranian program, but would prompt a war with Iran, possibly escalating to regional conflict. Sanctions and sabotage, Dagan keeps indicating, are the way to counter the Iranian drive to the bomb. Anything else is “stupid.”

Even Dagan’s hammering critiques have been overshadowed, however, by Diskin’s march onto the Iranian battlefield. In his comments Friday, he not only expressed doubts about the potential effectiveness of an Israeli military option. He didn’t merely reiterate Dagan’s concerns about starting a war whose scale and consequences were unpredictable. He also personalized the onslaught, declaring that he had “no faith” in the Netanyahu-Barak duo — no faith in what he called their “messianic” decision-making processes, no faith in what he suggested were their misleading presentations to the Israeli public, no faith in their ability to steward a military assault on Iran that might develop into war.

As with Dagan, the response has been an effort at character assassination. Ashkenazi and Dagan were speaking out, it was said, because they had wanted to stay on longer in their posts, or they were about to embark on political careers. So too Diskin, according to prime ministerial aides, would surely have resigned long before the end of his term if he were truly so scandalized by the incompetence of his political masters. In fact, though, he was speaking only because he was poised to enter politics (according to Barak), or was disgruntled at having been passed over for the top Mossad job (according to those in Netanyahu’s circle).

In the days since Diskin vented his criticisms, ministers have been lining up to take potshots at him. Some have aired the not unreasonable complaint that a man who was trusted with the state’s most sensitive information is breaching that trust by making public assessments based upon it. That, too, is a complaint that has been leveled against Dagan.

For those people — almost everyone, that is — who are not privy to the accumulated intelligence and consequent assessments of Iran’s nuclear program and how to stop it, there is simply no way to judge whether Netanyahu and Barak are right to declare that sanctions just aren’t working, that the moment of truth is mere months away and that, as Barak said just last week, “now is the time” for the international community to prepare to put the Iranian program to “a decisive end.”

There is no way of knowing whether Dagan, a seven-year Mossad chief, and Diskin, who ran the Shin Bet for six, overestimate what can be achieved by the clandestine means in which their agencies specialize. There is no way to gauge whether and how any personal frustrations, now that they find themselves outside the circles of real power, are impacting on their judgement.

After all, impressive though the track records of these ex-security chiefs may be, they are ex-security chiefs. For a year and more, they have been out of the loop. And whatever Dagan’s successor, Tamir Pardo, may think about tackling Iran, however Diskin’s successor Yoram Cohen judges the imperative for action, neither man has vouchsafed any assessment publicly.

Only one of the present trio of security chiefs, indeed, has gone public with an assessment of the nature of the challenge posed by Iran — the current chief of the General Staff. Ashkenazi steered his way through four years as IDF chief without ever giving a substantive interview to the written Israeli media. Gantz, 14 months into the job, spoke to Haaretz ahead of Independence Day last week.

He left no doubt that he regards the Iranian threat with the same kind of potential gravity as do Netanyahu and Barak. “If Iran goes nuclear it will have negative dimensions for the world, for the region, for the freedom of action Iran will permit itself,” he said. That freedom of action might be used “against us, via the force Iran will project toward its clients: Hezbollah in Lebanon, Islamic Jihad in Gaza. And there’s also the potential for an existential threat. If they have a bomb, we are the only country in the world that someone calls for its destruction and also builds devices with which to bomb us.”

But he also sounded somewhat less urgent than Netanyahu and Barak have done. “Clearly, the more the Iranians progress the worse the situation is,” he said. “This is a critical year, but not necessarily ‘go, no-go.’”

In contrast to the Netanyahu-Barak line, he also reportedly asserted — the Haaretz interview did not feature a direct quote on this — that international diplomatic and economic pressure on Iran is beginning to bear fruit.

But perhaps most strikingly, Gantz said Iran’s supreme religious leader Ayatollah Ali Khamenei has not yet decided whether he wants to advance the program “to the acquisition of a nuclear bomb” and that he didn’t actually think Khamenei would do so. Ultimately, he added, Iran’s leaders were “very rational.” That’s certainly not the thrust of the Netanyahu-Barak thinking.

The push to a bomb, Gantz said, “will happen if Khamenei judges that he is invulnerable to a response. I believe he would be making an enormous mistake, and I don’t think he will want to go the extra mile. I think the Iranian leadership is composed of very rational people. But I agree that such a capability, in the hands of Islamic fundamentalists who at particular moments could make different calculations, is dangerous.”

In the days since that interview, aides and advisers to Netanyahu, Barak and Gantz have sought to play down any impression of differences between the chief of staff and his employers. But the differences are plainly there.

In contrast to Gantz, Netanyahu told CNN last week that, where Iran’s leaders are concerned, “I don’t think you can bet on their rationality.” In contrast to Gantz, Netanyahu told AIPAC in March that, “Amazingly, some people refuse to acknowledge that Iran’s goal is to develop nuclear weapons.”

And Gantz is still in the loop, still privy to the latest classified information.

Curiously, ministers, aides and advisers to Netanyahu and Barak have not been lining up to take potshots at him. Ex-security chiefs are relatively easy prey; those who are still serving carry a certain aura of integrity — certainly those who are newish and unsullied in the job.

The best tactic here, the political leadership has evidently decided, is the finesse, not the confrontation. Criticism leveled at Gantz would likely bounce back… or, at the very least, further highlight the differences. Far more astute to quietly move on, and focus instead on softer targets.