Syrian government forces are pounding rebel-held districts of the strategic central city of Homs with air strikes and artillery, using what have become known as "Qusair rules" after the bulldozer tactics that produced a seminal victory for the regime in storming the rebels' western stronghold of Qusair in May.

Government troops used relentless bombardment of Qusair, which controlled vital supply routes in western Syria, to batter the city for two weeks before sending in a ground force largely made up of fighters from Hezbollah, the regime's Lebanese ally, battle-hardened by years of fighting Israel, into the ruins to wipe out the rebel defenders.

Hezbollah, like Syria and strategic ally of Iran, took heavy casualties in the fierce house-to-house fighting in Qusair, but finally crushed the rebels after three weeks of fighting to cut off the rebels' vital supply lines from neighboring Lebanon.

Now the forces loyal to embattled President Bashar Assad, fighting rebels armed by Saudi Arabia and Qatar and more recently a reluctant United States, are using "Qusair rules" against the rebels who hold 14 districts of divided Homs, an early epicenter of the 28-month-old insurgency against Assad and which once had a population of about 650,000.

With Qusair out the way, Assad's forces, which also include a growing number of Iraqi Shiite fighters trained and largely controlled by Iran's Islamic Revolutionary Guards Corps, Damascus has reopened links with the northwestern region that is the heartland of Assad's Alawite sect, an offshoot of Shiite Islam, and the key Syrian ports of Latakia and Tartous through which pass most of Assad's weapons shipments from Russia.

Now the regime is seeking to break a lengthy stalemate in Homs, where about 60 percent of the buildings are reported to have been destroyed or too damaged to be inhabited during months of fighting.

Syrian troops advanced into the Khaldiyeh district Monday after bombarding the rebel-held area for 10 days, rebel activists reported.

"Starting Friday, regime troops started to advance slowly, seizing several buildings on the edges of Khaldiyeh," a rebel activist named Yazan reported via the Internet.

"The most heated battles are taking place in Khaldiyeh and Bab Hud ... . The situation's very difficult here. If nothing changes, Homs will fall."

Syria's state news agency, SANA, reported government troops were moving forward in Bab Hud, which is in the city center, amid heavy clashes.

The Syrian Observatory for Human Rights, an opposition group in London monitoring the conflict, said shelling had damaged the 13th century Khaled Ibn al-Walid mosque on the edge of Khalkdiyeh. Video footage uploaded by rebels shows heavy explosions and thick columns of smoke pouring from the landmark mosque.

Activists said Hezbollah fighters, part of a force of Lebanese Shiite fighters reportedly numbering 2,500-4,000 men in Syria, were spearheading regime forces battling their way into the rebel areas -- just as they did in Qusair. This time they appear to be supported by fighters from the National Defense Army, a 50,000-strong militia formed by the regime and trained by Hezbollah and the Revolutionary Guards' elite Al-Quds Force, its covert action arm that has long worked with Hezbollah.

There was fierce fighting in Homs, dubbed "capital of the revolution," when the uprising against Assad began March 15, 2011. The districts held by the rebels have been under siege and constant artillery bombardment for more than a year.

By all accounts, the rebels are being squeezed hard in the current offensive that began June 29, because they're cut off from the supply of arms now coming from the West via Turkey in the north and Jordan in the south.

The regime forces have vastly superior firepower and, as they did in Qusair, are concentrating it on battering Homs into submission as part of Damascus' grand offensive.

It's clear the regime's steadily gaining ground as Assad seeks to cement control of the territory between Damascus, most of which he holds, and the Alawite stronghold in the north, apparently seeking to push the rebels out of the center of the country.

Another offensive including a large Hezbollah force is gathering pace further north against Aleppo, where rebels also hold ground. For now the main focus is Homs, but Aleppo, once Syria's commercial heart, is expected to face "Qusair rules" too.

END