The nearly nine-year U.S. military engagement in Iraq officially ended late last year – on Sunday, Dec. 18, to be exact –when a convoy of 500 troops in 110 vehicles left a base near the city of Nasiriya at 2:30 a.m. and headed southward. The convoy, guarded by overhead aircraft, rolled into Kuwait at around dawn, ending the United States’ most costly and domestically divisive war since Vietnam.

In departing, the Americans left behind a tiny U.S. residual force whose tasks are to protect the massive U.S. Embassy, assist in training Iraqi soldiers and facilitate arms sales worth $11 billion.

Like Israel’s stealthy withdrawal from southern Lebanon in 2000, the details of the United States’ pullout from Iraq were deliberately kept secret to ward off possible attacks by anti-American insurgents.

That such precautions were deemed necessary speaks volumes about the parlous condition of Iraq as a new year begins.

Speaking at a White House ceremony to mark America’s departure from Iraq, U.S. President Barack Obama accentuated the positive, declaring that Iraq had become a “sovereign, self-reliant and democratic” nation and a model for democracy in the Arab world. But striking a more balanced note, Obama observed that the U.S. role in Iraq would ultimately be judged by history.

The Obama administration, having inherited a war from president George W. Bush that claimed the lives of 4,487 Americans and cost U.S. taxpayers a whopping  $1 trillion, has no illusions what may lie ahead now that the United States has terminated combat operations in Iraq.

In a sober assessment, U.S. Defence Secretary Leon Panetta said, “Let me be clear: Iraq will be tested in the days ahead…” Within 48 hours of the U.S. withdrawal, two separate developments validated his sombre prediction about Iraq’s future.

A political crisis erupted when Iraqi Prime Minister Nuri Kamal el-Maliki, a Shiite, issued an arrest warrant for Vice-President Tariq al-Hashimi, a Sunni. Maliki accused him of running death squads to assassinate politicians and government officials. The accusation, heatedly denied by Hashimi, threatened an American power-sharing arrangement and summoned up the twin spectres of sectarianism and civil war yet again.

And in a reprise of the endemic violence that has convulsed Iraq since 2003, car bombs and improvised explosives shattered markets, apartment buildings and schools in Baghdad, killing 70 Shiite and Sunni civilians in the worst day of bloodshed in about a year.

Taken together, these events cast doubt on the ability of the country’s quarrelsome ruling elite to forge peace and stability in Iraq, a nation that has stumbled from one disaster to the next in the past 30 years.

Saddam Hussein, Iraq’s paramount leader from 1979 to 2003, led Iraq astray by waging war with Iran – its regional rival – in 1980 and by invading Kuwait in 1990.

Iraq’s invasion of Iran touched off the longest war in the annals of the modern Middle East and cost Iraq dearly in terms of casualties and property damage and arrested development. Iraq’s incursion into Kuwait, repelled by a coalition of countries in the 1991 Gulf War, led to United Nations sanctions that crippled and isolated Saddam’s brutal Baathist regime.

Washington, which had long hewed to a policy of dual containment in dealing with Iraq and post-revolutionary Iran, invaded Iraq in an attempt to stabilize the Middle East and make it more American-friendly.

The United States’ military involvement in Iraq was preceded by its invasion of Afghanistan in the fall of 2001. The Bush administration struck Afghanistan to unseat the Islamic fundamentalist Taliban regime, which had harboured Al Qaeda, the organization that had ordered the destruction of the World Trade Center in Manhattan on Sept. 11, 2001.

The Bush administration, mired in an increasingly difficult war in Afghanistan, stretched its resources by targeting Iraq. Washington claimed that the Sunni regime in Iraq possessed nuclear, chemical and biological weapons of mass destruction, and that Saddam, a prototypical secular Arab dictator, had co-operated with Al Qaeda’s supreme leader, Osama bin Laden.

The first of these claims seemed plausible, but the second one was always highly questionable. Neither proved to be true, tarnishing Washington’s credibility.

Once in Iraq, the United States found itself woefully ill-prepared to fight an insurgency, which has been largely characterized by a sickening spate of suicide bombings. By 2006, Iraq was slipping into a civil war pitting the majority Shiites against the minority Sunnis. In response to this crisis, Washington resorted to a “surge,” dispatching yet more troops to Iraq. Within about a year, the United States had deployed 170,000 troops in Iraq. To an extent, the “surge” achieved its objective.

In a further effort to tamp down the spiral of violence, the United States co-opted Sunni tribal leaders in “Awakening” formations to combat Al Qaeda in Mesopotamia – an Al Qaeda franchise group – in restive Anbar province. The strategy, though somewhat successful, has not eliminated Al Qaeda as a threat.

Alongside these efforts to defeat the insurgents, consisting of a coalition of Islamists, disaffected nationalists and common criminals, the United States tried to improve everyday life, restore oil production to prewar levels and build a culture of democracy.

Almost a decade on, Washington’s greatest achievement in Iraq was in uprooting the Baathist regime, in removing Iraq as a military threat to Israel, and in liberating Iraqis from Saddam’s serial violations of human rights and his wasteful hegemonic ambitions. Iraqis are free at last, as exemplified by their unfettered access to the Internet and cable TV.

The liberation of Iraq may have been an underlying cause of the so-called Arab Spring, the popular rebellions that have ousted authoritarian leaders in Tunisia, Egypt and Libya.

Today, Iraq has all the trapping of a multi-party Jeffersonian democracy. A constitution has been written and transparent elections have taken place. In practice, however, Iraqi democracy is still a fragile flower that may yet wilt. Critics charge that Maliki, the prime minister, is a polarizing figure whose aim is to marginalize opponents and create a one-party state.

The Americans, to the best of their ability, papered over the deep sectarian divisions that continue to divide Shiites, Sunnis and Kurds. But now that they are gone, observers fear that members of Iraq’s security forces will be more loyal to their respective sects rather than to Iraq itself. Last week, Turkish Foreign Minister Ahmet Davutoglu warned that Sunni-Shiite sectarian tensions would be suicidal for the entire region.

Although violence is generally on the wane, Iraq still remains very volatile, with 500 to 750 attacks having been recorded per month in 2011. Nonetheless, street life in Iraqi cities has virtually returned to normal.

Anti-American feelings, fanned by Iran, are deeply embedded in Iraqi society. Moktada al-Sadar, a pro-Iranian Shiite cleric whose militia fought the Americans in two uprisings in the city of Falluja in 2004, has warned that U.S. diplomats and contractors are now fair game.

In retrospect, the United States left Iraq in better shape in terms of health care, education, sewage management and accessibility to electricity and potable water. But most Iraqis receive only a few hours of electricity a day, and oil production lags far behind 1970s levels. Indeed, an agreement on dividing Iraq’s oil wealth has eluded its fragmented leadership.

At the start of 2012, Iraq is a budding democracy. But its flawed leadership and its unresolved problems may yet shape and define Iraq for years to come.