Israel has long complained about Syrian President Bashar al-Assad’s alliance with Iran, his support for the Shiite militia Hezbollah and his sheltering of leaders from Palestinian militant groups, such as Hamas, in Damascus.

But with Assad facing the most serious threat to his rule since he took power nearly 11 years ago, Israelis have been forced to confront the notion that they may well be better off with him than without him.

Assad, like his father before him, has ensured that the Israeli-Syrian border has remained Israel’s quietest front for decades, enabling that country’s northern residents to flourish in an atmosphere of relative peace even as the two nations remain technically in a state of war.

The possibility that the fundamentalist Muslim Brotherhood or radical groups could rise to power in place of Syria’s secular, stable leadership has prompted fear among some Israelis. Watching the Muslim Brotherhood gain a foothold in Egypt’s political system after the ouster of President Hosni Mubarak has only fed an Israeli squeamishness about the prospect of regime change in Damascus.

As one member of Israeli Prime Minister Binyamin Netanyahu’s cabinet put it, “We know Assad. We knew his father. Of course, we’d love to have a democratic Syria as our neighbor. But do I think that’s going to happen? No.”

For now, there is little that Israel can do other than sit and monitor the demonstrations in Syria, which have drawn thousands to the streets over the past 10 days and led to clashes with security services, leaving at least 60 people dead. On Tuesday, the Syrian cabinet resigned in an effort to prop up Assad, who is expected to lift a repressive emergency law and ease other restrictions.

“We’ve had a dictator, but it’s been very quiet,” a senior Israeli military commander said.“On the other hand, it’s absolutely clear to us that the Syrians play a negative role” in the region.

Syria, whose leadership is Alawite, a minority that constitutes an offshoot of Shiite Islam, has long supported Iran and its Shiite ally in south Lebanon, Hezbollah. Although Israel sees Iran as Hezbollah’s chief patron, officials regard Syrian support as no less crucial.

Israeli military officials say the majority of weapons that Hezbollah has stashed in south Lebanon since a 2006 conflict with Israel were made or supplied by Syria, including short-range Scud missiles as well as 302mm rockets, which, when fired from southern Lebanon, could reach Tel Aviv.

Syrian officials have denied supplying weapons to Hezbollah. In April, after Israel first accused Syria of supplying the Scuds to Hezbollah, Hasan Nasrallah, the head of the group, refused to comment.

During a visit to Moscow this month, Israeli media reported, Netanyahu pleaded with Russia not to sell Syria anti-ship missiles for fear that they could be transferred to Hezbollah. But his request was rebuffed.

Israeli military officials said in interviews that most of Hezbollah’s weapons are covertly transferred by truck from arms depots near Damascus to storage facilities in southern Lebanon.

Israeli intelligence asserts that Hezbollah has built hundreds of bunkers and filled them with Syrian-made weapons, all since 2006, the last time Israel attacked the Shiite militia.

A map of alleged Hezbollah installations provided to The Washington Post this week by Israeli military officials identifies more than 550 underground bunkers, 300 surveillance sites and 100 other facilities.

In releasing the map, the Israeli military appeared to be trying to preempt international criticism of any future offensive against the alleged sites, many of which are located in residential villages alongside hospitals, schools and even civilian homes.

Military commanders say they want to avoid the kind of international rebuke Israel received after it launched an operation in late 2008 to try to stop Palestinian militants from firing rockets from the Gaza Strip into Israeli towns. About 1,300 Palestinians were killed in that offensive.

“Our interest is to show the world that the Hezbollah organization has turned these villages into fighting zones,” the senior Israeli commander said.

Israeli military officials and analysts said Assad’s departure could lead to a break in Syria’s support for Hezbollah.

“A different regime is not naturally an ally of Hezbollah and the Iranians,” said Ehud Ya’ari, a commentator on Arab affairs for Israel’s Channel 2 television station.

“People would very much like to see Assad gone and his whole regime replaced,” Ya’ari said in an interview. “That doesn’t mean they don’t have concerns about what’s coming next.”