JERUSALEM - Israeli intelligence and military officials have warned in recent days that if a peace deal isn't achieved soon the moderate Palestinian leadership in the West Bank could collapse and give way to more radical Hamas militants, backed by Iran and Syria, who already rule the Gaza Strip.

The warnings come as the United States makes a last-ditch effort to revive talks between Israel and the Palestinians that stalled almost as soon as they resumed in September.

Under a tentative agreement struck between Israeli Prime Minister Binyamin Netanyahu and Secretary of State Hillary Rodham Clinton, Israel would extend a partial ban on settlement construction for 90 days, and the U.S. would sell the country $3 billion worth of advanced fighter jets. The proposal is expected to be discussed Wednesday when Netanyahu's seven-member security cabinet convenes, though a vote is not expected until he receives written assurances on the package from the United States.

A senior Israeli West Bank commander cautioned in an interview Tuesday that negotiators have only a short window before the recent quiet there is broken. Today's calm "is not forever," the officer said, speaking on condition of anonymity. "If our political echelon won't get anything in these negotiation channels, we will face an escalation on the ground - in six months, nine months - something like that."

Improved security coordination between Israel and the Palestinian security services has helped usher in one of the quietest periods in Israel's 62-year history. But, the officer added, that could unravel quickly. "I'm not sure that the Palestinian security forces will be able to keep this good coordination or whether they will want to" if talks fail, the officer said.

Amid such worries, Israeli military planners are studying intensively what a third Palestinian intifada, or outbreak of violence, could look like and how they would respond. They also are warning Israel's political leadership of the possible outcomes of failed negotiations, the officer said.

Those concerns are reflected in the intelligence community, too. A senior Israeli intelligence official told reporters Sunday that the Palestinian security infrastructure could disappear "in five minutes" if the Palestinian leadership, led by President Mahmoud Abbas and Prime Minister Salam Fayyad, crumbles in the wake of failed talks.

In a recent interview, Fayyad expressed similar sentiments. "The most important thing that can happen now is for that turnaround in security to be validated politically," Fayyad said.

Deputy Prime Minister Dan Meridor, a member of Netanyahu's security cabinet, says the public debate about temporarily extending the building moratorium in Jewish settlements is a distraction.

"The freeze is not the main thing, rather the negotiations, which are an Israeli interest of the top order," Meridor told the Israeli newspaper Ha'aretz. "It is clear to all of us that the present situation cannot remain as it is."

That Meridor made such observations is particularly noteworthy. He is no dove, but he is an ardent member of Netanyahu's hard-line Likud party that has long been cool to territorial concessions.

"There has been no terror in the past year and a half, and the Palestinian economy is experiencing unprecedented growth, so that there is a relatively comfortable feeling," Meridor continued. "But it's an illusion to think that the situation can remain as it is. This is not a normal situation. Israel has an interest in creating a border, with Israel on the one side and the Palestinian state on the other."

The recent calm has made resolving the dispute with the Palestinians seem less urgent for some Israelis. But there are many potential consequences for Israel's longer-term security, internal character and standing in the world should negotiations fail.

A dissolution of the Palestinian Authority could prompt a full Israeli reoccupation of West Bank towns that already have been transferred to Palestinian control, prolonging Israel's rule of the territory. The prospect of a broader Middle East peace with countries such as Syria and Lebanon, in that event, would dissipate.

Israel also could grow more isolated internationally. A delegitimization campaign against Israel by left-wing activists, academics and artists abroad has intensified, with calls for boycotts of Israel because of its ongoing rule in the West Bank.

There is also the question of how Israel can remain a democratic state with a Jewish majority without territorial compromise.

"I've reached the painful conclusion that keeping all the territory means a binational state that will endanger the Zionist enterprise. If we have to give up some of the territory, or give up the Jewish and democratic character [of the state] - I prefer to give up some of the territory," Meridor told Ha'aretz. "It is impossible to ignore reality."

Amid these warnings, Netanyahu has tried to reassure the Obama administration that he is serious about negotiating a peace deal while promising his political allies - who want to hold on to the West Bank for ideological, religious or security reasons - that he won't give up too much.

But Aaron David Miller, a former U.S. peace negotiator, said failure to reach an agreement would bring real consequences: "Bottom line if it fails: The Israelis will keep their state, but the Arabs and Palestinians will never let them really enjoy it."