To explain Benjamin Netanyahu's frenzied reaction to the Geneva agreement on Iran's nuclear program, let me begin with the stack of brown cardboard boxes under my wife's desk.

Each of the five cartons contains a gas mask and related paraphernalia for a member of my family to use in the event of a chemical-weapons attack. They were delivered last January, as part of the gradual government effort to prepare every household in Israel for a rain of Syrian missiles. I suppose that having "defense kits" in the house could be macabre, but what we usually notice is that they're a nuisance: another thing on which to bang your toe in an overstuffed city flat.

What's more, they're apparently an obsolete nuisance. A couple of weeks ago, the usual nameless military sources told the local media that the Defense Ministry would recommend ending production of gas masks for civilians. According to the leaks, intelligence assessments said that the Organization for the Prohibition of Chemical Weapons was successfully reducing Syria's poison-gas arsenal. In other words, the U.S.-Russia agreement on Syria's chemical weapons is working, and one result is a significant improvement in Israeli security.

To put it mildly, this isn't what Prime Minister Netanyahu expected in September when President Barack Obama opted for a diplomatic solution rather than a punitive attack on the Assad regime for using chemical arms. Back then, Netanyahu barely concealed his view that American weakness was both a catastrophe and a betrayal that would encourage Iran to develop nuclear arms. At a military ceremony, he proclaimed that Israel could depend only on itself. "If I am not for myself, who is for me?" Netanyahu said, quoting the first half of an ancient Jewish maxim, without the second part, which says that someone who is only for himself is nothing. "We are for ourselves!" he declared. A nameless senior official, making the prime minister's warning more explicit, said that "a diplomatic failure in Syria without [an American] military response" might force Israel to attack Iran. The failure of diplomacy was virtually a given; the only question was what would come after.

The Syria agreement was the warm-up act for the interim accord with Iran. This time the hostile Middle Eastern state is a greater regional power, and the weapon of mass destruction to be tamed is nuclear rather than chemical. Pressure was exerted through American-led economic sanctions, rather than deployment of American forces for a military offensive. No one can yet be sure that the interim deal will lead to a full agreement to keep Iran from getting a bomb. But the immediate steps promise an improvement in Israeli security. Among other measures, Iran has obligated itself to a complete halt in developing the Arak reactor, which potentially could produce plutonium, and has agreed to tight inspections to insure that it is keeping the deal.

Instead of toasting Obama's success, Netanyahu has responded with public fury perhaps unprecedented in the Washington-Jerusalem relationship. "What was achieved last night in Geneva is not an historic agreement; it is an historic mistake," he said, in a public statement before television cameras. He concluded with a renewed threat, "Israel is not bound by this agreement…. Israel has the right and the obligation to defend itself, by itself, against any threat. As prime minister of Israel, I would like to make it clear: Israel will not allow Iran to develop a military nuclear capability."

The link between Netanyahu's reactions in September and now is what could be called Agreement Anxiety Disorder (AAD): a reflexive certainty that any time an antagonist is willing to make an agreement to end or manage a conflict, the deal is a deception. The only safe agreement would be one in which you make no compromises or concessions, so that you are ready to fight the inevitable next round. Since agreements sans compromises are rare, the very thought of making a deal ignites something between panic and fury, and any friend who advises you to accept the agreement is betraying you.

To be fair, some agreements are tricks, and some well-intentioned agreements just come undone. AAD is a political expression of post-traumatic stress: Past experience is so terrible that you have to be ready for every new event to repeat it. Trauma can build a filter in the mind: Anything that confirms you are under attack registers. The experience of safety doesn't. If you're an Israeli, you might have a hard time noticing that the peace treaty with Egypt has held up for over 30 years. The suicide bombings of the Second Intifada are entirely, horribly visible, and either prove that the Oslo Accord of 1993 was a Palestinian trick—or, at best, that the best intentions fail. My point here is not a political analysis of how Oslo broke down, which would include Israel's role in the collapse. I'm talking about gut feelings. If you are an older Israeli of an older generation, you remember that the United Nations pulled its peacekeeping troops out of the Sinai in 1967 just because Egyptian President Gamal Abdel Nasser asked it to. Expect perfidy.

As this train of thought indicates, Israelis come by post-traumatic stress honestly. But not everyone is equally affected; far from it. Some people learn from war that you should make peace. For Netanyahu, the Munich Pact reveals where all peace agreements will lead, and the British shutting the doors of Palestine to Jews in 1939 shows great powers must never be trusted. His AAD is so intense it should disqualify him from public office, and at the same time resonates with a significant portion of voters.

A realistic analysis of the agreement with Iran acknowledges risks and potential achievements, and compares them to the risks and potential of alternative policies. An Israeli military strike, or even an American one, would slow but not stop Iran's effort to become capable of building a nuclear bomb. It would also confirm Iran's fear that only a bomb would make it safe.

With an effort at empathy, one can understand Netanyahu's anxiety. But Agreement Anxiety Disorder does not lead to good analysis. It doesn't produce advice that American senators or representatives should accept when choosing their own response to the Iran deal. He knows how to speak your fears, but the poor man is not thinking clearly.