The Syrian regime has made some initial gains in its swelling offensive in the strategic Qalamoun Mountain region, which means there are probably going to be more suicide bombings in Lebanon like Tuesday's deadly jihadist attack on the Iranian Embassy in Beirut, an analyst says.

The regime claims its forces have captured the key town of Qara, 60 miles north of Damascus, after three days of heavy fighting that began Friday. The assault in the mountain region that runs from Damascus westward to the border with Lebanon was carried out under a major aerial and artillery bombardment of rebel positions.

If Qara has fallen, it marks a victory for Hezbollah, the powerful Lebanese Shiite movement whose fighters are spearheading the much-anticipated offensive that's aimed at driving rebel forces out of the Qalamoun region that dominates Syria's critically important M5 north-south highway.

If the offensive succeeds it will deal a potentially crippling blow to the rebels, cutting off their main supply lifeline for men and weapons from Syria's western neighbor Lebanon along the Qalamoun corridor, 50 miles long and 25 miles wide that runs to the northern outskirts of Damascus, the divided Syrian capital.

At the same time, the forces of embattled Syrian President Bashar Assad have been making gains in opening a path into the contested northern city of Aleppo, once Syria's commercial hub, reversing more than a year of steady rebel gains.

The regime has also concentrated efforts to regain several south Damascus suburbs long held by Assad's enemies -- all this as the rebels have been badly weakened by in-fighting.

Hezbollah, and its patron Iran, are largely responsible for keeping Assad, Tehran's key Arab ally, in power in the 32-month-old civil war against Sunni rebels battling to topple him.

If the rebels lose Qalamoun, their forces around Damascus will be isolated, opening the door for Assad to regain total control of the battle-scarred seat of power. Rebel forces in the north and south would be cut off from each other.

Hezbollah's key role in the offensive, which some analysts believe could be the decisive battle of the conflict, reportedly involves a large force of several thousand seasoned fighters.

Some reports go as high as 15,000 men. But that would essentially mean Hezbollah's entire military force, including reserves.

It's unlikely to have weakened its front against Israel to such an extent, or left its Lebanese strongholds in south Lebanon, the Bekaa Valley in the northeast and in south Beirut undefended, particularly against rival Sunni militants who support the Syrian rebels Hezbollah is fighting.

Tuesday's double suicide bombing against the Iranian Embassy in Beirut, a command center through which Tehran and its Revolutionary Guard Corps coordinate with Hezbollah, underlined that threat on the movement's home front.

At least 23 people were killed and more than 150 wounded in the attack, the first time Iran, Hezbollah's backer, has been directly targeted in Lebanon over the Syrian war.

Hezbollah's strongholds have come under attacks several times in recent months because of its involvement in Syria, and its security in Beirut has been tight.

So the embassy attack marked a major security breach that could signal an escalation in Sunni-Shiite conflict in Lebanon at a time when the fate of the politically polarized country hangs in the balance.

More and more, events in Lebanon are dictated by what transpires in Syria.

"Recent Syrian government gains around Damascus, Aleppo and now the northern Qalamoun have resulted in a further escalation in sectarian sentiment ," observed analyst Charles Lister of IHS-Jane's Terrorism and Counterinsurgency Center in London.

"The apparent involvement of one or both of Hezbollah and Iranian military personnel in recent military gains makes the targeting of those actors' assets abroad much more likely. Attacks like this one are likely to continue."

Hezbollah units, including special forces units, are reported to have been given operational control of the southern, western and northern sectors of the Qalamoun front.

They've got Syrian air and artillery support, but it looks like Hezbollah's pretty much running an offensive that could decide the outcome of the war.

"Hezbollah is poised to play its biggest role yet in the Syrian civil war," the U.S. global security consultancy Stratfor observed.

It said this could potentially trigger "the largest spillover of violence into Lebanon since the start of the Syrian war."