JERUSALEM — As the streets of Gaza exploded with celebration on Friday night with masked Hamas militants marching defiantly to cheer the resignation of President Hosni Mubarak of Egypt, Israelis reacted with quiet and deep concern because the regional leader on whom they had relied most was suddenly gone.

The government of Prime Minister Benjamin Netanyahu maintained the same studied silence it has sustained for more than two weeks on the assumption that nothing it said could serve its interests: if it praised the pro-democracy movement, it would be seen as disloyal to its ally, Mr. Mubarak. If it favored Mr. Mubarak, it would be dismissed as a supporter of dictatorships.

But behind the scenes, officials willing to share their thoughts anonymously expressed worry because they believed that whoever followed Mr. Mubarak would be less friendly to Israel.

“We don’t know who will be running things in the coming months in Egypt, but we have to keep two things in mind,” one top official said. “The first is that the only example we have of this kind of thing in the region is Iran in 1979. You can’t take that out of your mind. The second is that if Egypt pulls back in any way from its peace with Israel, it will discourage anyone else in the region, including the Palestinians, from stepping forward. So the regional implications for us are significant.”

The official said it was more likely than not that Egypt would maintain its peace treaty with Israel and added that, in any case, relations with Israel would probably not be among the first concerns of the incoming Egyptian authorities.

Omar Suleiman, the former head of Egyptian intelligence who was recently named vice president by Mr. Mubarak, has long-standing relations with Israel and is respected here. But his role seems subordinate, at best, to the military council that appears to be running Egypt. Still, relations between the Israeli and Egyptian defense establishments have long been cordial. But officials worry that cooperative efforts could slow or halt.

Earlier this week, Mr. Netanyahu did speak publicly in Jerusalem about Egypt before a group called the European Friends of Israel. He laid out three possible situations if Mr. Mubarak resigned. “There are many possible outcomes beyond the liberal, democratic models that we take for granted in our own countries,” he said.

“First, Egyptians may choose to embrace the model of a secular reformist state with a prominent role for the military. There is a second possibility that the Islamists exploit the influence to gradually take the country into a reverse direction — not towards modernity and reform but backward.

“And there’s still a third possibility — that Egypt would go the way of Iran, where calls for progress would be silenced by a dark and violent despotism that subjugates its own people and threatens everyone else.”

Benjamin Ben-Eliezer, a former defense minister who developed a friendship with Mr. Mubarak over some 20 years, said by telephone — and also on Israeli television — that he had spoken with Mr. Mubarak hours before his Thursday night speech to the nation. Mr. Mubarak, he said, seemed to know he had no choice but to leave — and Mr. Ben-Eliezer agreed. But Mr. Mubarak saw great peril ahead.

“He spoke about a snowball that was starting to roll, which would not leave a single Arab state untouched in either the Middle East or North Africa,” Mr. Ben-Eliezer said. “He spoke of his disappointment with the Americans. He said, ‘You will have to grow accustomed to one fact — that you’re going to live in a radical Islamic world, and no one can promise what will happen tomorrow.’ For me, he was one of the pillars of the peace process.”

Israel’s entire strategic outlook relies in some fashion on its three-decade peace with Egypt. Thanks to the treaty, its military has minimal presence on its southern border, freeing it up for actions to the east and north; about 40 percent of Israel’s natural gas is imported from Egypt; Egypt has been supportive and helpful in negotiating with the Palestinians; Egypt has played a big role in stopping the smuggling of weapons and militants into Gaza, and in helping Israel in its blockade policy aimed at squeezing Hamas.

The other regional countries that have diplomatic relations with Israel — Jordan and Turkey — have cooled significantly in recent years, especially after Israel’s 2006 war in Lebanon and its 2008-9 war in Gaza.

The marches in Gaza on Friday, a rare open display by armed uniformed militants on the streets, showed that the Egyptian policy toward Hamas would most likely change and had, in fact, already loosened. The border has been breached repeatedly in the past two weeks by Hamas, which has brought back its militants from Egyptian prisons. Hamas officials are calling on Egypt to open its border with Gaza completely. And last weekend, a gas pipeline in the Sinai exploded, apparently as a result of sabotage, disrupting the supply to Israel and Jordan.

The marchers in Gaza chanted against Mr. Mubarak and also against President Mahmoud Abbas of the Palestinian Authority, whom they consider a traitor. One of Israel’s fears is that the decline of Mr. Mubarak will strengthen Hamas and weaken the more moderate Palestinian Authority.

Eli Shaked, Israel’s ambassador to Cairo from 2003 to 2005 and deputy ambassador there from 1989 to 1992, gave a bleak analysis of Egypt’s prospects to move toward democracy, saying by telephone that it had too few institutions, educated people and political parties to move to a democratic system. He feared that the only force organized enough to take over was the Muslim Brotherhood, which he described as anti-American, anti-Israel and anti-peace.

http://www.nytimes.com/2011/02/12/world/middleeast/12israel.html

It is not always about what Israel wants!!!!!.