The Iraqi government recently reversed its support for Syrian President Bashar Assad amid the ongoing unrest in Syria, and is now calling on Assad to step down. However, it is true that many Iraqi Shiites deeply fear the possible consequences of an overthrow of the Alawite-dominated regime in Damascus.

Specifically, the Shiites' concern is that hard-line Sunnis might come to power next door and embolden Iraqi Sunnis, reigniting sectarian violence and civil war in Iraq. As one anonymous, senior Iraqi Shiite politician put it to Reuters: "Change in Syria will cause major problems for Iraq. They [Sunnis] will incite the western [Sunni] part of Iraq." However, are these anxieties justified?

In a word: No. To understand why, it is necessary to examine the question of what was primarily responsible for the dramatic drop in violence in Iraq from 2007 onward.

The prevailing orthodoxy affirms that the increase in the number of U.S. troops and the introduction of a counter-insurgency strategy as part of the "surge" were the key factors behind the weakening of Al-Qaeda and the Sunni turn against the militant group. However, such reasoning imputes too much game-changing power to the American military and belittles the importance of local Iraqi actors and factors. In fact, Sunni insurgents began to turn against hard-line militants because by late 2006 they had realized that they were losing the sectarian civil war in and around Baghdad against Shiite militias. At the time these were protected by Prime Minister Nouri al-Maliki.

It is a truism that a key reason for the swelling of the ranks of the Sunni insurgency after 2003 was the de facto transformation of the de-Baathification process into a "de-Sunnification" process. This was most flagrant in the disbanding of the old, Sunni-dominated Iraqi military by L. Paul Bremer, the head of the Coalition Provisional Authority. In hindsight, it is easy to point the finger solely at Bremer for this grave mistake. Yet as The Independent journalist Patrick Cockburn has noted, Bremer was backed and encouraged in his decision by Shiite and Kurdish politicians who were eager to fill the ranks of the new Iraqi security forces with their own militiamen.

Nevertheless, de-Sunnification alone cannot account for the manner in which the Sunni insurgency gained recruits and strength. In any war, no side commences hostilities if it does not feel that there is a good chance of defeating the enemy. In this case, a key premise behind the insurgency was that the Sunnis were in the majority and could thus either subdue or wipe out Shiites in a sectarian civil war.

The "Sunni-majority" delusion was well illustrated prior to the invasion, when Sunni Arabs frequently accused outside demographers of under-representing their numbers. Those accusations were not mere rhetoric. The propagation of this false perception among Sunnis was partly the result of propaganda put out by Saddam Hussein's regime, and partly the consequence of a sense of disconnect from the majority Shiite population, created by 70 years of Sunni minority rule.

Having launched repeated attacks on the Shiites, causing large numbers of casualties, the Sunni insurgency was able to provoke the Shiite militias into retaliation. This gave rise to a full-blown sectarian civil war in 2006 centered on Baghdad. The main aim of both sides was to seize control of the mixed Sunni-Shiite neighborhoods in the capital and cleanse them of the rival sect.

Owing to numerical advantage and backing from the central government, the Shiite militias largely succeeded in clearing the mixed neighborhoods of Sunnis. This forced the Sunni insurgents to retreat into the few remaining Sunni-majority strongholds of the city, such as Yarmuk, or flee the country to Jordan and Syria. In the latter two countries, Nir Rosen, an investigative journalist and reporter, interviewed numerous Sunni insurgent leaders who admitted that they had lost the battle against the Shiite militias in Baghdad.

Hence, the sectarian civil war subsided throughout 2007 and 2008 for the same reason wars generally end: namely, one side had mostly lost its will to fight. Fearing further losses at the hands of the Shiite militias and the central government, large numbers of Sunnis realized, at around the time the surge began, that the only feasible option was to cooperate with coalition troops and Iraqi security forces against the likes of Al-Qaeda. This led to the rapid strengthening of the Anbar Awakening and the birth of the Sons of Iraq movement.

Maliki would go on to reel in the Shiite militias, such as Muqtada al-Sadr's Mahdi Army. The prime minister realized that the remaining Sunni insurgency posed no existential threat to his government, opening the way for him to consolidate his power base by cracking down on Shiite militants based in the south and around Baghdad.

The risk of another sectarian civil war in Iraq on account of turmoil in Syria is very low indeed. Having witnessed the disastrous outcome for Sunnis of the sectarian civil war in 2006, the Sunni Arabs of Iraq generally appreciate that they cannot afford to take on Shiites in another conflict. For most of those in the community, the concern is not to return to minority rule. It is to survive and adapt to the reality that Iraq's Shiite majority is leading the country's political process.