The double veto by Russia and China of a U.N. Security Council resolution on political transition in strife-torn Syria appears to sound the death knell for a diplomatic solution and herald an all-out civil war that will destabilize the Middle East.

Lebanon and probably Iraq, Syria's neighbors where sectarian tensions are already high and getting worse, will more than likely be dragged into the maelstrom.

Israel, which sees itself facing an unprecedented threat from a sustained missile bombardment by its foes, is also jittery that the Persian Gulf confrontation between the West and Iran, Syria's ally, could trigger a region-wide conflict in which it will be a target.

Israel's political and military leaders have escalated threats to unleash pre-emptive military strikes against Iran's nuclear facilities, sharply heightening regional tensions.

All in all, the Middle East, a crucible of war for more than 60 years, has been gripped by alarm and uncertainty as it's convulsed by the political upheaval of the Arab Spring in which four tyrants have been toppled by their own, long-downtrodden people.

The 11-month-old uprising in Syria, with an estimated body count of 6,000, has become the bloodiest front line of the Arab Spring.

And unless Moscow and Beijing can soon convince Syria's embattled president, Bashar Assad, whose father founded the regime in Damascus in 1970, on some kind of transition of power, the country may explode into a sectarian conflict between the ruling Alawite minority and the Sunni majority.

Indeed, Western analysts say the double veto will only accelerate the slide toward civil war.

That could, in the end, play into U.S. hands and Washington's desire for regime change in Damascus to block Iran's drive to establish an arc of influence through Iraq, Syria and Lebanon.

Russia and China saw the U.N. resolution as the precursor of Libya-style Western intervention to achieve political and economic objectives -- a pattern they feared could work against them in the future.

In the run-up to Saturday's Security Council vote, Assad, possibly encouraged by the backing of Moscow and Beijing, ordered his forces to unleash artillery and tank fire on key centers of the uprising, reportedly killing 200-300 people.

U.S. President Barack Obama branded the slaughter an "unspeakable assault" but the double veto left the international community bitterly divided and seemingly helpless as the bloodletting intensified.

It may not have been solely coincidence that the sustained shelling marked the 30th anniversary of the massacre of up to 30,000 Sunni Muslims in the city of Hama in western Syria by Assad's strongman father, Hafez Assad.

On Feb. 3, 1982, Hafez Assad sent thousands of troops into Hama to begin a bloodbath that crushed an uprising by the Muslim Brotherhood. His forces shelled Hama for three weeks, razing much of the old city.

Even in the violence-plagued Middle East, the Hama slaughter was mind-numbing in its obliterating intensity.

In recent weeks, Hama has been the scene of bloody fighting as anti-regime forces, which launched the uprising with unarmed street protests, increasingly take up the gun.

In the wider, geopolitical context, the Russia-China double act points to trouble ahead as Moscow and Beijing strive to fill the vacuum left by the United States' ebbing power in the Middle East.

The events unfolding in Syria and the Persian Gulf are linked. If Assad falls, Iran loses its gateway to the Levant and its expansionist thrust westward.

"In the expansion of Iranian influence, Syria is now the major battlefield," observed U.S. security consultancy Strafor.

Russia is backing Assad, including with the supply of advanced weaponry, because he's Moscow's last chance of restoring its Cold War influence in the Arab world. China supposedly just wants access to the oil.

Now, says veteran Indian analyst M.K. Bhadrakumar, "with the double veto, the only option available for the U.S. and its allies in Syria is to flout both international law and the U.N. Charter and overthrow the regime in Damascus."

In that regard, Philip Giraldi, a former CIA officer, writes in The American Conservative that "unmarked NATO warplanes are arriving at Turkish military bases close to Iskenderun on the Syrian border" where the rebel Free Syrian Army is based.