On 19 November 1977, Egypt's then president, Anwar al-Sadat, became the first Arab leader to set foot on Israeli soil. Four years earlier, the two nations had been at war; two years later, their leaders reached the agreement at Camp David that led to peace. It was a cold peace, one shaped by realpolitik rather than popular empathy, but it has lasted for more than three decades.
In the words of one Israeli diplomat, Sadat's appearance on the steps of his plane melted the hearts of all Israelis. The mythology may shroud the facts of the time - Sadat, after all, had been looking for a settlement since 1971 - yet it is difficult to overstate the political, strategic and economic importance of the subsequent peace treaty. That is why, however remote the prospect of an Islamist takeover in Egypt, Israel is watching events unfold across its southern border with a sense of foreboding. And why one Israeli newspaper asked this month: "Can Israel only make peace with dictators?"
The Egyptian peace is the cornerstone of Israel's defence strategy, says Michael Herzog, a former brigadier general in the Israel Defence Forces and chief of staff to the defence minister until 2009. The deal with Sadat, which also opened the way for a 1994 treaty with Jordan, all but ended
the threat of a conventional war on Israel's two longest borders. The dividend is clear: defence spending, though still high by international standards and supplemented by US aid, is less than 10 per cent of GDP, a third of what it was in the 1970s. Further, Egypt plays the role of co-ordinator, brokering talks between Israel and the Palestinians, attempting to secure a rapprochement between Fatah and Hamas and taking on radical Islamism. The ties don't end there. Israel relies on Egypt for 40 per cent of its natural gas supply.
That Israel has much to lose helps explain why its normally off-message coalition government is maintaining a disciplined silence about events in Egypt - in public, at least. How can the Middle East's "only democracy" be against a popular uprising?
Yet what are the chances of a Muslim Brotherhood takeover in Egypt? The last time pro-Brotherhood candidates fought an election, in 2005, they won 20 per cent of available seats, but predicting their appeal post-Mubarak is difficult. Most estimates put membership of the Brotherhood at 600,000, in a country of 80 million. Katerina Dalacoura, author of a forthcoming book, Islamist Terrorism and Democracy in the Middle East, says the Brotherhood lacks the manpower and leadership to take control. She plays down the notion that the group is extremist, arguing that it is politically cautious. This is no longer the movement of Sayyid Qutb, whose writings inspired the founders of al-Qaeda and Islamic Jihad.
The tweeters and facebookers of Tahrir Square are not seeking an Islamist Egypt, and ultimately the army - recipient of most of the $1.5bn a year in US aid and power broker in any change of regime - will act to prevent it. "The peace with Israel is very unpopular. But nobody quite talks about what the alternative would be," Dalacoura says. "Is Egypt going to declare war on Israel? It is very unlikely."
More likely is that the relationship between Egypt and Hamas will change.
The suffocating Gaza blockade, put in place after Hamas took control of the Palestinian territory in 2006, is dependent on Egyptian police manning their 11-kilometre common border. In a post-Mubarak world, Hamas could have free rein. Moreover, Israel fears that a weakening of ties with Egypt will in turn ease the strategic pressure on Iran. Syria and Hezbollah-controlled southern Lebanon will be emboldened, while swing states in the Gulf will reassess their options.
Jordan is different. King Abdullah has kept the opposition, including the Muslim Brotherhood, close. It may be a cynical ploy - his change of cabinet was a game of musical chairs - but so far it is working. There is tension between east Jordanians and majority Palestinians. If push comes to shove, says Herzog, the east Jordanians will rise to defend the regime.
Another possible scenario would be an uprising among the Palestinians in the occupied West Bank, inspired by events in Tunisia, Egypt and elsewhere. Israel appears reluctant to restart the peace process with the Palestinians at a time of instability, exposing once again its blind spot to a root cause of its regional difficulties. Were it to seize the opportunity to bring Mahmoud Abbas and the Palestinian Authority back to the table for talks and make substantial progress towards a two-state solution,
Tel Aviv would mitigate against public animosity in the region. Abbas's position will be further weakened, should Hamas benefit from improved relations with a new Egyptian government, so the motivation to act now is clear. As Sadat told the Israeli press in November 1977, explaining why he sought peace: "The alternative is horrible."
Jon Bernstein is deputy editor of the NS