He is also the last leader of Israel’s Labour Party to have led the country. He defeated Benjamin Netanyahu in 1999. Since then, the left has struggled consistently in elections but, speaking to the JC this week, Mr Barak believes they can succeed again.
“In democracies the pendulum moves from side to side. Sometimes it takes a long time,” he says.
“The right wing is temporarily more popular. Part of this is the endemic problems of the left.
“In short, the right-wing electorate act like football fans — they are always there for the team, they don’t change their mind if their team loses three times. The left-wing electorate behaves like a debate club in Oxford.
“They gather in air-conditioned rooms, top-quality people discuss issues [and] how the world should look, rather than how it operates in reality and what should be done in order to achieve power and change direction.”
He points out, however, that “the two cases in the last generation of the left-wing winning elections — Rabin and myself — in both cases [Labour was led by] a person with prestige in security who was not perceived as a politician.”
Mr Barak comes across as profoundly pragmatic. He has been vocal in his call for Israel to leave the West Bank, for instance. “The issue is over the way Israel is heading. The debate is painful but simple: in the region there live 13 million people, 6.5m Jews and 6.5m Arabs.
“If there is only one political entity in this area named Israel, this entity will become inevitably either non-Jewish or non-democratic.
“This bloc of millions of Palestinians clearly have political aspirations. [If they] would vote for a Knesset as part of a binational state, within a few years this binational state will have an Arab majority and permanent civil war.
“[But] if they cannot vote, that’s not democracy. Neither is the Zionist dream.”
There is potential for a viable, demilitarised state for the Palestinians, he says, that is “not my dream but part of the reality — they are there and I see no alternative”.
Similarly, he is equally pragmatic about last week’s clashes on the Gaza border. He says it is possible to handle several hundred demonstrators at close range, but techniques do not yet exist for when the numbers reach many thousands.
The protesters could not be allowed to cross the frontier, he says, because “there are either settlements or kibbutzim, moshavim, infrastructure, 100 yards from this fence”.
“Probably there is — I assume people are working on it now — some creative idea of what means might be developed to hold a demonstration of 10,000 people far away from you, at a few thousand yards. But it was not available here.”
Above all, however, Mr Barak is deeply concerned at the direction in which Israel is heading, a threat he describes in his book as “existential”.
“In Israel the very institutions of democracy are under continued attack by its own government, like an auto-immune disease,” he says.
“There is even an attack on the very basic values of the IDF. What happened with Elor Azaria [a soldier jailed for shooting an incapacitated Palestinian knifeman] is a classical case. The IDF— the officers, the leadership, the generals — were defending the basic values of the IDF: you kill first whoever tries to kill you, but once someone is not a risk anymore you don’t execute people without due process.
“So you ask yourself, why the hell, when Israel is so strong, our government is running an attack on the very basic institutions of democracy?”
He describes himself as one of Mr Netanyahu’s “harshest critics”, after serving alongside him in the army and later in government as defence minister in the 2009-2013 coalition.
“He’s not a lightweight, he’s a thoughtful and knowledgeable person and now also experienced — but he’s wrong, the policies are wrong.”
Mr Barak projects a sense, however, that it is hard for people who have not been Israeli prime minister to truly understand the dilemmas they have had to grapple with.
In his memoir, Mr Barak describes a conversation with Barack Obama on a possible military strike against Iran.
“We hear that even people high up in your military, in military intelligence and the Mossad, are against it,” the then-president said.
Mr Barak did not deny it.
“We highly respect our top people in the military, and in intelligence. We make a point of listening to them before taking action,” he responded.
“But here’s the difference. When they look up, they see Netanyahu, or me. When Bibi and I look up, we see heaven.
“Whoever is up there, we clearly can’t go to Him for advice. We are responsible for Israel’s security.”
