While Egyptians are celebrating President Hosni Mubarak's ouster after 18 days of protest, Israelis are increasingly concerned that his departure will empower the Islamist Muslim Brotherhood and threaten Israel's longstanding peace treaty with Egypt.
Analysts in Israel are warning that the power vacuum left behind by Mr. Mubarak could eventually lead to the rise of the Brotherhood, one of the minor players in the predominantly secular protest movement that led to the end of Mubarak's reign. They worry that could create an Egypt that is antithetical to the Jewish state.
The Muslim Brotherhood, which was founded in 1928, has established its popularity through social and charity institutions and performed well in the 2005 parliamentary elections before the regime stepped in to limit its gains.
''If there is a free election I don't see how they can be stopped,'' says Eli Shaked, former Israeli ambassador to Egypt. The Brotherhood's success, he says, would boost Islamists throughout the region, including in Jordan, where antigovernment protests have been inspired by the protests against Mubarak.
''The Muslim Brotherhood has already said they won't be committed to the peace treaty. I don't see a military conflict with Israel. But the whole regional order of the last 30 years will be totally shattered,'' Shaked says.
''If the Muslim Brotherhood comes out so successfully in Egypt, it will boost other Muslim brotherhoods in Jordan and the West Bank. Then Jordan is in trouble, even Syria might find itself under threat. The domino effect might impact also on Saudi Arabia,'' he says.
What Mubarak meant for Israel
For Israelis, Mubarak has been absolutely crucial to their sense of regional stability. Through wars and uprisings, Mubarak adhered to the peace treaty with Israel, chastising Arab radicals that the days of Egypt warring with Israel were over. Egypt joined Israel in blockading the Gaza Strip in a bid to undermine its Hamas rulers and was a de facto ally against the spread of Iranian influence in the region.
Unlike the US, Israel did not turn against Mubarak during the crisis. In fact, according to a Haaretz report, Israel called on the US and Europe to curb their criticism of Mubarak ''in a bid to preserve stability in Egypt'' and the wider Middle East.
Zvi Mazel, another former envoy to Cairo, says: ''We're not against democracy in Egypt, but we are really afraid and it is legitimate for us to say we are afraid of what will come out from this."
The stability of moderate Jordan has also become a source of grave concern for Israel.
''Israel had several very important strategic foundations. One is the peace agreement with Egypt and the second are the relations with Jordan, the strategic partnership. There is now a concern that both of these will be overturned,'' says Shlomo Brom, senior analyst at the National Institute for Security Studies in Tel Aviv.
Jordan's strategic position
Muslim Brotherhood ascendancy would probably cause Israel to view its southern front as an active military arena. If they do gain power "the whole balance of the Middle East will change and Israel will have to invest a lot in building facilities to deal with Egypt,'' says Yaacov Amidror, a retired major-general who was research chief for the Israeli army.
Jordan, traditionally a reliable ally against the common foe of Palestinian nationalism, is looking increasingly shaky in recent days. After several demonstrations inspired by the Egyptian protests, King Abdullah appointed a new cabinet headed by the new prime minister Maarouf al-Bahit and said he would undertake ''reforms, modernization, and development''
"At the moment, it looks as if the king is in control of the situation. But we've seen what's been happening in recent weeks and we know the situation can change very quickly,'' says Mr. Brom.
In the view of Alon Liel, former director-general of the Israeli foreign ministry, the ouster of Mubarak will complete the ''encirclement'' of Israel by hostile states in the region, taking it back decades to a posture of isolation.
It will push forward a process that has already seen Turkey change from an ally to an acrimonious rival, especially after Israeli forces stormed a Turkish aid flotilla and killed nine activists.
''My guess is that Egypt will start behaving like Turkey is behaving," says Mr. Liel. "They will not ruin the peace agreement with Israel but will be much more critical of Israel for not progressing on the peace track, especially the Palestinian track. They might pull the ambassador without breaking diplomatic relations. We have to get ready for moves from Cairo that will be a more true reflection of what the Egyptian public feels toward Israel.''
Israel, Liel says, is in its weakest regional position in decades.
''Even before the peace with Egypt we always had an anchor in Iran or Turkey. Now we are losing everybody. We don't have Iran, we don't have Turkey, and if we don't have Egypt, those are all the three main players," he says. "It was always very important to have at least one of them on our side. Now with encirclement we are being pushed back two to three decades to the feeling of core isolation.''