Most Israelis were either born or immigrated to this country during the period in which Hosni Mubarak ruled Egypt. This is the reality they know. And this is the significance of the stability that Mubarak provided them with.

In all the upheavals that took place in the Middle East over the past three decades, the Egyptian regime appeared to be a powerful rock. The leaders of Israel knew that their left flank was secure as they went out to war, built settlements and negotiated peace on the other fronts. The friction in relations between Jerusalem and Cairo, however frustrating it was at times, did not undermine the foundations of the strategic alliance created by the Israeli-Egyptian peace agreement.

The resignation of Mubarak following 18 days of protests in Egypt ushers in a new era of uncertainty for the entire region, and for Israel in particular. The long reign of the Egyptian leader was not unusual for the Middle East. Hafez Assad led Syria for 30 years, like Mubarak in Egypt; King Hussein and Yasser Arafat ruled for 40 years. But when they stepped off the stage, their legacy was secure. Hussein and Assad passed the reins on to their sons, and Arafat was replaced by his veteran deputy, Mahmoud Abbas. This is why the changing of the guard in Jordan, Syria and the Palestinian Authority were perceived by Israel as natural, arousing no particular concern. After all, the familiar is not all that frightening.

But this is not the situation in Egypt today. Mubarak was thrown out, before he could prepare one of his close aides or his son to take over as president. The army commanders who took over are trying to calm the Egyptian public and the international community with promises that they have no intentions of setting up a new junta in Cairo, but rather, plan to pass to transfer authority to a civilian government through free elections. But no one, including the generals in the Supreme Council of the Armed forces, knows how and when the regime transition will play out. History teaches us that after revolutions, it takes a number of years of domestic infighting before the new regime stabilizes.

This uncertainty troubles Prime Minister Benjamin Netanyahu. His reactions during the first days of the revolution exposed deep anxieties that the peace agreement with Egypt might collapse. He tried to delay Mubarak's end as long as possible, but to no avail, and on Saturday he praised the Egyptian military's announcement that all international agreements would be respected, including the peace treaty with Israel.

Netanyahu is afraid of the possibility that Egypt may become an Islamic republic, hostile to Israel - a sort of new Iran but much closer physically. He hopes this doesn't happen and that Egypt will follow Turkey's footsteps, preserving formal ties with Israel, embassies, air connections and trade, even as it expresses strong criticism of its treatment the Palestinians.

The best case scenario, in his view, even if it is less likely, is that Egypt will become like Turkey before the era of Erdogan: a pro-American country, controlled by the military.

Netanyahu shared with Mubarak his concerns about the growing strength of Iran. Egypt played a key role in the Sunni, the "moderate," axis, which lined up alongside Israel and the United States against Mahmoud Ahmadinejad and his allies in Lebanon, Syria and the Gaza Strip.

The toppling of the regime in Cairo does not alter this strategic logic. The revolutionaries at Tahrir Square were motivated by Egyptian national pride and not by their adoration of the Islamic Revolution in Iran. Whoever succeeds Mubarak will want to follow this line, even bolster Egyptian nationalism, and not transform Egypt into an Iranian satellite. This does not mean that Mubarak's successor will encourage Israel to strike the Iranian nuclear installations.

On the contrary: they will listen to Arab public opinion, which opposes a preemptive war against Iran. Israel will find it difficult to take action far to the east when it cannot rely on the tacit agreement to its actions on its western border. Without Mubarak there is no Israeli attack on Iran. His replacement will be concerned about the rage of the masses, if they see him as a collaborator in such operation.

Whoever is opposed to a strike, or fear its consequences - even though they appear to be in favor, like Netanyahu and Defense Minister Ehud Barak - now have the ultimate excuse. We wanted to strike Iran, they will write in their memoirs but we could not because of the revolution in Egypt. Like Ehud Olmert says that he nearly made peace, they will say that they nearly made war. In his departure Mubarak prevented a preemptive Israeli war. This appears to have been his last contribution to regional stability.