How is this possible?
Simple, just check the history of the Sunni Arabs and what we now know as Iraq. Until 1918 there was no Iraq, just three provinces of the Turkish (Ottoman) empire. These were Mosul province (which was largely Kurdish, with a large Turk minority), Baghdad (which was largely Sunni Arab, with a large Shia minority) and Basra (mostly Shia Arab.) When the conquering British came in after 1918, they took these three provinces and declared them the new country of Iraq. As was their custom (in dealing with colonial matters), the British left the current governing arrangements in place. This meant that the Sunni Arab minority was running things.
How did this happen?
Again, it's all a matter of history, and the continuation of ancient trends. The best organized, and most powerful gang in what we now know of as Iraq has been, for several centuries, a collection of like minded Sunni Moslem groups living in and around Baghdad. This great city was founded, over a thousand years ago, by the Arab conquerors of what was then called Mesopotamia. The city became a center of Islamic learning, and a major commercial power because of its location in the fertile Tigris-Euphrates river valley, with all those trade routes. But that wealth attracted conquerors. The Mongols leveled the place in 1258, and trashed the place again in 1400. The Persians, who often controlled the region before the Islamic empire showed up, returned in 1524. The Ottoman Turks finally conquered the region 1638 and set about getting the area organized to suit Turkish tastes.
The Turks were practical, and brutal. Putting troops inside the major cities took care of controlling the urban areas. But there were dozens of major tribes in the rural areas that were a major headache. The Turks made deals with the larger tribes, often involving annual payments to the tribal chiefs, to keep the peace. This meant not raiding Turkish controlled territory, and sometimes policing the lesser tribes. Keep in mind that from the Mongol destruction of the area in 1258 until about 1850, the population of modern day Iraq fluctuated between a million and 1.3 million people. The Turks then began to introduce better water, sanitation and health care, leading to a population explosion, and the current Iraqi population of about 26 million.
When the British moved in, Iraq was such a backwater that the job was left to the colonial government in India. In effect, Iraq as a state was a creation of the old British Indian army between 1919 and 1922. British and Indian officials created Iraq, and until 1932, the Indian rupee was Iraq's official currency. More importantly, the Sunni Arab officials the Turks had relied on to run the three provinces (Mosul, Baghdad and Basra) were still running the place.
The Turks relied on the Sunni Arabs for two reasons. First, they were Sunni. When the Ottoman Turks pushed the Shia Iranians out of the area in the 17th century, they were doing it partially for religious reasons, for the Ottoman Sultan (emperor of the Turkish empire) was also the Caliph (leader of all Sunni Moslems). The Iranians were not only a distinct ethnic group (Indo-European), but were Shia Moslem. The Sunni Moslems considered the Shia a deviant form of Islam and relations between the two sects has always been strained. The Shia consider the Sunni illegitimate, but that's another story. When the Iranians occupied Baghdad and Basra, they put Shia Arabs in charge. The Turks weren't stupid, they needed loyal allies in their newly conquered provinces, and the Sunni Arabs were the natural choice.
But there was another reason for putting the Sunni Arabs in charge, they were, along with the Jewish minority, the most educated and capable group in the area. The Sunni Arabs had long dominated trade, education and social life in Baghdad. The Sunni Arabs saw the Turks as saviors from the hated Shia Iranians. It was a mutually favorable deal, and for over three centuries, the Sunni Arabs of Baghdad prospered as the minority in charge.
Sunni Arab men not only joined the civil service, but they also dominated the leadership of the police and military in the region. When, in 1918, the British marched in as the new conquers, they found the Sunni Arabs agreeable, the Kurds and Shia Arabs less so. Actually, the most agreeable were the Christian minorities, who had been persecuted by all the Moslems for over a thousand years. But the Christians were less than two percent of the population. There were more than ten times as many Sunni Arabs, and the Sunni Arabs really knew how to terrorize a majority population. In short, the Sunni Arabs could control the Shia Arabs, who outnumbered them by three-to-one.
To further complicate things, the British attached the province of Mosul to this new nation Iraq. Mosul was actually part of the Turkish homeland. But oil had recently been discovered in Mosul, and the British did not want the new Turkish republic to have oil, just in case the Turks should, later in the 20th century, decide to attempt reforming their empire. So now the Iraqi Sunni Arabs had to dominate the Kurds as well, something they had not had to do in the past. The Kurds were not Arabs, but Indo-European, like the Iranians. The Kurds of the region had been trying, for thousands of years, to establish their own state. They were never able to do it, and resisted attempts by others to govern them.
The British set up Iraq as a constitutional monarchy in the 1920s, with a parliament and everything. Everything, that is, but cooperation between the various ethnic and religious groups. Since the Sunni Arabs dominated the government, economy, military and monarchy (the royal family, political exiles from Arabia, were Sunni), they dominated the country.
The Sunni Arabs had learned well from the Turks, and applied the right amounts of terror and persuasion to keep everything under control. Democracy, however, was a bother. So Sunni Arab generals staged a coup in 1958, murdered the royal family, and established a dictatorship. This lasted until the last Sunni Arab dictator, Saddam Hussein, was deposed in 2003.
Now you understand. In 2003, the apparatus of Sunni domination, was taken apart. Sunni Arabs no longer held nearly all the senior military, police and government jobs. The Sunni Arab secret police force(s) were disbanded, as was the army. For the first time in over three centuries, the Sunni Arabs of Baghdad were not in charge, and they did not like it. They have been resisting this change in status ever since. But in the last three years, things have only gotten worse for the Sunni Arabs. The new government (dominated by Kurds and Shia Arabs, who are 80 percent of the population) has created an army and police force. So not only are the Sunni Arabs outnumbered, but they are confronted with an army and police force controlled by their enemies.
And it gets worse, because the Sunni Arab dictatorship got worse as time went on. The last 10-15 years of Saddam's rule were particularly horrible for the Kurds and Shia Arabs. There were massacres and constant terror from Saddam's secret police. So not only are the Sunni Arabs now outnumbered, and facing over a quarter million soldiers and police they do not control, they are also on the receiving end of revenge attacks by millions of enraged Kurds and Shia Arabs.
This is not the recipe for civil war, it's the prelude to massacre and mass expulsion. Of the Sunni Arabs. In Iraq, everyone is aware of this, but too many foreigners, including many who should know better, just don't get it.
People who should know better, including diplomats, and those just looking for an exciting headline, are talking up civil war in Iraq once more. You can't have a civil war if one side is so weak that it's unable to raise an army and put up much of a fight. In that case you have the weaker side expelled, wiped out, or forced to accept whatever terms the stronger side will grant. In this case, the Sunni Arabs of Iraq have the short end of the stick. The Sunni Arabs in Iraq never comprised more than 20 percent of the population. Emigration in the past three years, to avoid the violence, and vengeance of Shia and Kurds, has reduced that to fifteen percent. But the worst thing that's happened to the Sunni Arabs, is the creation of an effective non-Sunni Arab army and police force. The Sunnis Arabs are outnumbered and outgunned, and facing the growing threat of massacre and expulsion from Iraq.