Amid heavy fighting between opposition fighters and Syrian government forces, a blaze swept through the historic market area of the city of Aleppo on Saturday night.

“Rebel” militias launched an offensive on Friday to seize control of Aleppo’s central marketplaces, or souks, which are considered strategically vital to control the city. The labyrinth of narrow alleyways that make up the Old City provides cover for fighters to move around the heart of the city and access the adjacent neighborhoods.

Opposition spokesmen claimed that Syrian army and police snipers have taken up positions in the ancient citadel of Aleppo, which towers over the Old City. There have been reports of heavy shelling by government forces of areas seized by the “rebels,” with both sides in the conflict blaming each other for the fires that threaten to destroy many historic sites.

A separate offensive by opposition forces in Damascus over the weekend resulted in an estimated 64 deaths in the capital city’s suburbs.

The “rebel” surge inside Syria’s two main cities is the latest escalation of the long-running proxy war between the United States and its regional allies, on one side, and the regime of Syrian President Bashar al-Assad, backed by Iran, on the other.

The intensified fighting in Syria coincided with Washington’s announcement Friday that it would send additional aid to the opposition militias. The Obama administration declared that it would provide an extra $45 million of “non-lethal” aid to anti-Assad groups, bringing total direct US financial support for the Syrian opposition to $170 million.

According to the US State Department, the latest supplies will include “more than 1,100 sets of communications equipment, including satellite-linked computers, telephones, and cameras, as well as training for more than 1,000 activists.” Such equipment allows the US-backed militias on the ground to coordinate operations with their CIA and Turkish army handlers.

Direct US aid only makes up a fraction of the total support granted by Washington to the Syrian opposition. The Obama administration, through the operations of the CIA inside Turkey, oversees the supply of financial and military support from Saudi Arabia, Qatar, Jordan, Lebanon, and Turkey to various anti-Assad militants.

Washington has also ramped up its diplomatic offensive to isolate the Assad regime. During a press conference in New York on Friday, US Secretary of State Hillary Clinton announced that the Iraqi government of Nouri al-Maliki had been pressured into conducting “random searches of Iranian aircraft en route to Syria.”

The Maliki regime has until now sought to balance the dictates of its US masters with the growing economic and political ties that Iraq has with its neighbors in Iran and Syria. Clinton’s announcement that the US proxy war against Syria has been extended into Iraqi airspace only underscores the bullying and reckless character of Washington’s role in the region. The seizure of Iranian civilian aircraft and their cargoes by Iraqi air defenses, acting under the control of the Pentagon, would amount to a declaration of war between the two countries.

As Washington has ramped up its diplomatic saber-rattling, the fighting inside Syria has sharply intensified in recent days, with hundreds of casualties and widespread damage reported in and around Aleppo, the largest city and main commercial center of Syria.

Aleppo is one of the great cultural centers of the Middle East, with many buildings and archeological treasures dating back to the classical Islamic period, the Roman Empire, and even earlier civilizations. The central Aleppo souks, where fires and gunfights now rage, are widely regarded as among the finest and best-preserved examples of medieval architecture in the region. The alleys, shops and public squares of Old Aleppo have been given world heritage status by UNESCO.

This rich heritage, the cultural preserve of mankind, is endangered by the criminal policies of the United States government and its regional allies, which are sponsoring a sectarian Islamist opposition in an effort to destabilize and oust the Assad regime.

Thousands of civilians in Aleppo and across Syria have been killed in the months of fighting between opposition and government forces, while hundreds of thousands have been forced to flee their homes. The Syrian conflict has taken on an increasingly sectarian character, with the US, Turkey and the Gulf monarchies sponsoring Sunni Islamist militants battling the Assad government.

One of the main armed opposition forces waging the current offensive in Aleppo is the Tawhid Brigades. Led by Sunni extremists like Abu Khalid, a 28-year-old Syrian veteran of the sectarian civil war in Iraq, the Tawhid militia is one of the largest armed groups loosely associated with the opposition Free Syrian Army (FSA).

Speaking to McClatchy Newspapers in March, Khalid, then based in Jordan, admitted that his organization was running guns into Syria using money provided by the Sunni Gulf sheikdoms and the European powers. “We don’t mind any kind of cooperation,” even from the US, Khalid told a McClatchy journalist. “Our goal now is to end the regime, even if another million people are killed,” the opposition leader added.

While they have gained the sponsorship of Washington and its regional allies, the armed opposition groups have failed to win a significant base of support among the working class and small businessmen in either Aleppo or the Syrian capital, Damascus.

Pro-opposition activists inside Aleppo have estimated that there are around 6,000 “rebel” militants in the city – out of a total population of over 2 million people. Many of these fighters, including elements linked to Al Qaeda and the Libyan Islamic Fighting Group, have come across the nearby border with Turkey under the auspices of the CIA.

The US proxy war in Syria is plunging the country ever further into a nightmare of sectarian bloodshed, while destabilizing the entire Middle East. After a brief lull following the killing of US personnel in Libya by an Islamist militia, which produced a debate within Washington about the use of similar terrorist outfits in Syria, it now seems that US operations against the Assad regime have fully resumed.

The escalation of fighting, which will only intensify after the November US presidential elections, threatens to ignite a regional war with the potential to bring even greater calamities to the Middle East and the world.