Tuesday, President Trump unveiled his plan to end the Israel-Palestinian conflict, which, among other things, attempts to assuage Israeli worries about maintaining defensible borders. Evelyn Gordon, looking to a recent vote in the Jordanian parliament, argues that these will continue to matter because “hatred is strong and peace is fragile.”

If you want to understand the true obstacle to Mideast peace, look no further than the Jordanian parliament’s unanimous approval last week of a bill to ban natural-gas imports from Israel, just days after the gas began arriving. Energy-poor Jordan needs a stable, affordable fuel supply, which the Israeli deal provides. . . . But that doesn’t interest Jordanian lawmakers. What they care about is that this is “the gas of the enemy,” to quote protesters against the deal. They also don’t care that Jordan and Israel signed a peace treaty 25 years ago.

The deal will most likely go ahead despite parliament’s objections because King Abdullah, though happy to let his lawmakers spout anti-Israel rhetoric, rarely lets them interfere with anything that he considers an important Jordanian interest. . . . But regardless of what happens to the gas deal, the vote shines a spotlight on two errors that have consistently undermined Western peacemaking efforts.

The first is underestimating the depth of Arab hatred for Israel, and therefore failing to grasp that this is the principal obstacle to peace. . . . [A]s the Jordanian vote shows, neither peace nor prosperity is a prime motivator for many people in this part of the world, whereas hatred is a very powerful motivator.

The second major Western fallacy is that peace obviates the need for defensible borders. . . . The unabated hostility to Israel among most of its neighbors, coupled with the uncertain future of any agreement signed with a dictator, means that Israel can’t afford to assume any treaty is permanent. It must be prepared to defend itself if a new Arab government scraps the treaty. Indeed, both the Jordanian and the Egyptian treaties were drafted with that in mind, and that’s also why even Israel’s main center-left party insists on retaining the Jordan Valley in any deal with the Palestinians.

Two extraordinary events demonstrate something important about Israel’s most fervent adversaries. One was a speech given at something called The People’s Forum (funded generously by Goldman Sachs), which stated, “When the state of Israel is finally destroyed and erased from history, that will be the single most important blow we can give to destroying capitalism and imperialism.”

The suggestion that this tiny state is the linchpin of a global, centuries-old phenomenon like capitalism goes well beyond anything resembling rational criticism. Even if Israel were guilty of genocide, apartheid, and oppression—which of course it is not—it would not follow that its destruction would help end capitalism or imperialism.

The other was an anti-Israel protest that took place in front of New York City’s Memorial Sloan Kettering Cancer Center, deemed “complicit” in Israel’s evils. At organizers’ urging, participants shouted their slogans at kids in the cancer ward, who were watching from the windows. Given Hamas’s indifference toward the lives of Gazan children, such callousness toward non-Palestinian children from Hamas’s Western allies shouldn’t be surprising. The protest—like the abovementioned speech—deliberately conveyed the message that Israel is the ultimate evil and its destruction the ultimate good, cancer patients be damned.

The fact that Israel’s adversaries are almost comically perverse does not mean that they can be dismissed. If its allies fail to understand the obsessive and irrational hatred that it faces, they cannot effectively help it defend itself.