A tragedy is unfolding in Syria, as government forces continue to bombard Homs, the country's third largest city. The relentless shelling of Homs, a city of some 1 million people, along with the barbarous treatment of the opposition in the rest of the country, has ensured the eventual collapse of President Bashar al Assad and his regime. The only questions are when, and how the rest of the world can bring about that collapse as quickly as possible.

Make no mistake, Syria is not Libya. We are not dealing with a largely nomadic nation of 6 million people whose government had been hollowed out by a despotic Moammar Gadhafi. Instead, we are dealing with a country of some 22 million people whose antecedents go back several thousand years. Damascus is regarded by many historians as the oldest continuously inhabited city in the world. According to local legend, Cain lies buried in the hills nearby. Paul walked the streets of Damascus in Biblical times, while the city became the first capital of the growing Muslim empire in the wake of the Prophet Muhammad's death. Modern-day Israel, like Lebanon, was once part of Greater Syria in the days of the Turkish Ottoman Empire, an empire that finally ended with World War I.

Modern Syria was created in the wake of the First World War, when it became a French League of Nations Mandate. It got its independence from France in 1946. Similarly, Palestine, Iraq and Transjordan (later Jordan), like Syria, were formerly Ottoman territories that became British League of Nations mandates, and all subsequently became independent following World War II, with part of Palestine declaring its independence as Israel in 1948. In other words, all these countries, under one name or another, have had a closely connected history for at least 2,000 years. That is both their strength and weakness, as each tries to forge a future rooted in an often violent past.

Unlike Libya, Syria has a formidable military. The armed forces, when mobilized, total some 650,000. It has at least several hundred modern jet fighters, supplied by Russia, a deep relationship that goes back to the days of the Soviet Union. It also has numerous air-to-air and surface-to-surface missiles. Russia has a permanent naval base at Tartous, on Syria's Mediterranean coast. In short, Assad has major military forces under his command. Confronting Assad is no easy matter, and doing so would entail major casualties for any outside force.

On the other hand, Assad has a built-in problem with the military, one that could conceivably bring down the regime. Assad is an Alawite, a heterodox off-shoot of Shia Islam. Alawites make up some 12 percent of the population, with the rest overwhelmingly Sunni. But Alawites make up about 70 percent of the some 200,000 career soldiers in the Syrian army. The officer corps is about 80 percent Alawite. The military's most elite divisions, the Republican Guard and the 4th Mechanized Division, which are commanded by Bashar's brother, are exclusively Alawite. But most of Syria's 300,000 conscripts and air force pilots are Sunni. Because of the large Alawite composition of the Syrian armed forces, its interests are closely allied with that of President Bashar al Assad and the Assad family.

That composition helps to explain the cohesiveness of the armed forces in the face of wide-spread resistance, and the willingness of the army to bombard the largely Sunni city of Homs. But that willingness runs the risk of alienating Syria's mostly Sunni population. Moreover, there are 300,000 conscripts and pilots in the armed forces who are mostly Sunni. The cracks in Syria's makeup are beginning to show, and that means not only disaster for the Alawite regime of Bashar al Assad, but possible disaster for Syria as a whole, as its tribal, ethnic and religious divisions are put to the test.

The country best suited to help bring down the regime is neighboring Turkey, where thousands of Syrian refugees have taken shelter. Turkey has armed forces that are at the very least a match for those of Syria. But intervention is a very risky business, and Turkey cannot be guaranteed success. Syria is Iran's principal ally in the region, and it is through Syria that Iran has passed arms to Hezbollah in Lebanon and Hamas in Gaza. Much is at stake here, and the unraveling if not collapse of the Assad regime would mean a major restructuring of the present political and military order.

And then there is the human cost. Aside from the risks, how much longer is the West prepared to witness the relentless and mounting slaughter without doing something? These are not easy times.

William Stewart, a former Foreign Service officer and correspondent for Time magazine, lives in Santa Fe. He writes weekly on current affairs.