We have always known that the rare examples of peace between Arabs and Israelis were built on a fragile foundation. Now cracks in that foundation have started becoming more visible, and they are making ominous sounds as they grow.

It’s a reminder that the future of peace will require a different kind of engineering.

I am referring to the first peace treaty signed by Israel and an Arab state, Egypt, and the only other one, establishing peace between Israel and Jordan.

Each of these treaties, and the ensuing relationship between Israel and the only two Arab states with which it was at peace, depended on relationships with one man, the man in charge. Peace never included the population at large. There has never existed peace between the Israeli and the Egyptian people, but between Israel and the Egyptian dictator — just one man, whose rule always looked like it would end in disaster.

By necessity, the treaties were signed on the Arab side by unelected rulers. Egypt’s Anwar Sadat blazed the trail of peace in the 1970s, and Jordan’s King Hussein followed in 1994. The treaties held up well in the sense that no fighting war erupted. But animosity against Israel never let up.

There was peace above ground. But bubbling under the surface, in the streets, the people of Jordan and Egypt — particularly Egypt — held nothing but bitter contempt for Israeli Jews.

The Egyptian writer Mona Eltahawy explained it best when she said Israel had become “the opium of the Arabs,” a way for failed Arab leaders to intoxicate their own people, making them blame Israel for all their problems.

The opium has stopped working, and throughout the region Arabs blame their unelected dictators for the mismanagement, poverty and corruption that plagues their countries. But the hatred of Israel remains.

That simmering anger, that distorted image forged in the intoxicating cloud could eventually destroy the superficial peace that has survived until now.

The presidential campaign in Egypt brought repeated instances of candidates seeking to connect with voters by showing them how deeply they share their hatred of Israel.

The two finalists who will face off on June 16 and 17 have given vague pledges to stand by the peace treaty. But the candidate of the Muslim Brotherhood, Mohammed Mursi, has talked about putting the treaty to a referendum. And a referendum, polls show, does not bode well for the treaty.

Polls show profound animosity towards Israel more than three decades after the two neighbors made “peace.” Anti-Israel sentiment extends across all political and age groups.

Mursi is on record calling the Israelis “vampires.” As the top vote-getter in the first round, he has been careful not to antagonize Washington and its generous aid package by engaging in new anti-Israel rants. But his surrogates have had no such compunction.

During a campaign rally, Mursi watched and assented while the Islamist preacher Safwat Higazi told the crowd in a soccer stadium that Egypt under Mursi will usher in a new Islamic caliphate whose capital will be in Jerusalem, where Israel’s capital now stands. As Higazi cried out, “Our capital shall not be in Cairo, Mecca or Medina,” thousands chanted in unison, “Millions of martyrs march toward Jerusalem.” Over the loudspeaker Mursi supporters heard the call to “Banish the sleep from the eyes of the Jews.” The runner-up, who will face against Mursi in the runoff, is Gen. Ahmed Shafiq, former President Hosni Mubarak’s last prime minister. Shafiq has warned that the Muslim Brotherhood and Mursi would start a new war with Israel. But when voters have doubted Shafiq’s worthiness, his favorite achievement to cite is that he shot down two Israeli fighter jets. There could hardly be anything more heroic in the eyes of Egyptians.

In Jordan, King Abdullah remains in power and peace with Israel is not up for discussion at the moment. But just a few days ago, a small group of Israeli tourists came under attack in Jordan because, well, because they were Israeli. A local newspaper, al-Arab al-Yawm quoted a Jordanian explaining, “Those who talk about peace between Israelis and Jordanians are delusional. The signed agreements are . . . meaningless.”

The message is clear. Peace requires bringing people, not just rulers, together. Real, lasting peace requires a willingness of two peoples to live side by side. It’s not enough to have a dictator sign a “peace of paper,” or even put his fighter jets under lock and key. Without popular support, in the long run peace cannot survive.