Israel's electronic listening post atop Mount Hermon overlooking Damascus is working overtime as Israeli military chiefs monitor the accelerating collapse of the Syrian President Bashar Assad's Syrian regime in a 17-month-old uprising that became a civil war.

The Israelis, who've operated the intelligence-gathering base since 1967 when they captured the region's highest mountain and the southern sector of the volcanic plateau known as the Golan Heights, fear that trouble will explode on their northern border on a scale unseen since the 1973 Middle East war if Assad's regime is toppled.

That's the last thing Israel needs as it braces for trouble as well on its southern border with Egypt, which with Syria launched a surprise attack on Israel in October 1973.

That frontier that abuts Egypt's Sinai Peninsula became a threat for the first time since the countries' landmark peace treaty in 1979 following the ouster of President Hosni Mubarak, a staunch supporter of the pact, in another Arab revolution in February 2011.

Within the space of a few months, these two strategic borders, calm for more than three decades, have become flash points.

All this has happened as Israel braces for war with Iran, which the Jewish state may initiate with pre-emptive attacks on the Islamic Republic's nuclear program. That could ignite a regional conflict that, along with the political turmoil in the Arab world that shattered Israel's strategic policy by opening the way for Islamist governments for the first time, Israel views with great apprehension.

That may be the case in Syria as well if Assad's brutal regime is brought down.

With rebel forces increasingly assertive, blowing up Assad's key security chiefs July 18 and fighting pitched battles with regime troops in Damascus and Aleppo, Syria's second city and commercial heart, the Israelis say they believe the end is near for Assad.

Israel's greatest fear is that Assad -- or perhaps his hot-headed younger brother Maher -- will choose an apocalyptic end by unleashing Syria's chemical and biological weapons on missiles against the Jewish state.

Or perhaps, in the final chaotic days of the Assad dynasty, other forces, possibly even al-Qaida but more likely Hezbollah, could get their hands on these weapons of mass destruction while the fractious opposition forces argue about divvying up the spoils.

"What I expect to see in Syria is the definition of chaos, like what we saw in Libya -- various gangs vying for leadership and no initial central government," said Eyal Zisser, who teaches Middle Eastern Studies at Tel Aviv University.

Maj. Gen. Aviv Kochavi, chief of Israel's Military Intelligence, warned parliament last week that the regime's "is just a matter of time," while jihadist groups are moving into Syria, exploiting the power vacuum as the regime disintegrates.

The general feeling within the Israeli leadership is that the prospect of war with Syria is low even though the two countries remain technically at war.

Last week, Assad withdrew around half of the troops garrisoning the cease-fire line on the Golan to reinforce his units fighting rebels in pitched battles in the capital.

Even so, Defense Minister Ehud Barak says Israel may have to go in to seize or neutralize Assad's chemical/biological weapons to ensure extremists, such as Hezbollah in Lebanon, don't get them.

Syrian opposition leader Burhan Ghalioun has said if Assad's toppled an incoming Sunni regime would cut ties with Iran, Assad's key ally, and Hezbollah, Israel's longtime foe with whom it fought an inconclusive 34-day war in 2006.

That would be a great relief to Israel but only if there's a strong, united and more moderate successor regime in Damascus, rather than one inclined toward radical Islam -- and without weapons of mass destruction.

But it's more likely, the way things stand right now, that there's going to be a period of anarchy and settling of scores, with no single dominant force in charge, when Assad eventually goes.

The wholesale plundering of Moammar Gadhafi's arsenals, well stocked with advanced Russian weaponry, including surface-to-air missiles, and the violent aftermath of his fall that has spread across North Africa, up to Israel's southern border, provides a chilling vision of what could ensue if Assad's regime is crushed.

Mix Assad's chemical/biological weapons into the equation and there could be talk of apocalypse now.