When the last American soldiers left Iraq this week almost nine years after the fall of Saddam Hussein, U.S. officials were keen to portray it as a stable, democratic, if still troubled nation.
Just a few days later, the buffer of U.S. military presence gone, Iraq very quickly slipped back into the sectarian squabbling that pits Shi'ite against Sunni rivals and threatens to destroy their fragile power-sharing deal after only a year.
Prime Minister Nuri al-Maliki's Shi'ite-led government sought the arrest of his Sunni Vice President Tareq al-Hashemi accusing him of plotting assassinations while demanding parliament fire another rival, his Sunni deputy Saleh al-Mutlaq, after he compared Maliki to Saddam.
A cartoon in Al Sabaah newspaper captured the crisis: Two American soldiers in helmets talk, their backs turned on three men fighting for a share of Iraq.
We left them in peace and harmony, one American soldier says to the other as they walk away.
Iraqi Sunni discontent has grown since the ascent of the Shi'ite majority after the fall of Saddam, and many minority Sunni leaders now feel they have been marginalised, left out of the power structure by an increasingly authoritarian leader.
Shi'ites have worked in an uneasy, power-sharing agreement with the Sunni-backed Iraqiya party and Kurdish blocs for a year since the disputed 2010 election by splitting key posts: Iraq has a Shi'ite prime minister, a Kurdish president and a Sunni speaker of the house.
Maliki's moves against two Iraqiya rivals and the struggle between the Shi'ite leader and his Sunni opponents now risk spiralling into a wider struggle in Iraq, where sectarian sentiment always runs close to the surface.
Shi'ite leaders say the measures are against specific individuals and not Sunnis in general, but the timing of the moves against two rivals as the Americans leave is dangerously stoking Sunni fears of a Shi'ite push for more control.
Gambits like this are always risky; in the past, the United States often used its leverage to get him to back down, and the U.S. military presence helped reassure nervous Sunnis, said Stephen Biddle at the Council on Foreign Relations.
Now, of course, there is no such military presence and U.S. leverage is much smaller. That makes the stakes and the risks greater.
PLENTY OF RISKS
The renewed crisis risks scuttling the complex government set up where dozens of government posts are split among Shi'ite, Sunni and Kurdish blocs and bring Iraq closer to the sectarian tensions that triggered widespread slaughter in 2006-07.
Upheaval in Iraq could also have broader ramifications in a region where a crisis in neighbouring Syria is taking on a sectarian tone, and Shi'ite Iran and Sunni Turkey, with a nod from Sunni Arab Gulf nations, are increasingly jostling for influence.
Baghdad's Shi'ite-led government has moved closer to Iran, and a fall of Iran's ally, Syrian President Bashar al-Assad, whose Alawite sect is a Shi'ite offshoot, could shift power to Syria's Sunni majority on Iraq's doorstep.
Even the perceived presence of U.S. troops on the ground played a deterrent in Iraq's sectarian and ethnic mix between Shi'ite and Sunni, and between the central government and the Kurdish semi-autonomous region in the north.
The current situation suggests U.S. forces were a safety valve, wrote Iraqi columnist Alaa Hassan.
What happens next depends on how far Maliki's government pushes its investigations, how Sunnis react, and whether other third parties can bring them back from the brink.
In a flurry of meetings, U.S. officials, diplomats and Sunni and Shi'ite leaders have worked this week to calm nerves after Hashemi left to Iraq's largely autonomous Kurdistan region, where he accused Maliki of fabricating the charges against him.
This is a worrying situation that is being exacerbated by political rhetoric. Unless there is an effort to calm the situation and engage in dialogue, it could quickly spin out of control, said one Western diplomat in Baghdad.
Deep mistrust has already crippled the power-sharing agreement for a year, blocking deals on everything from a key hydrocarbons law to the appointment of vital security posts like the defence and interior ministers.
The dispute has roots in the 2010 election when Iraqiya won the largest number of seats with the support of many Sunnis but failed to muster a governing majority. Shi'ite parties formed a coalition that allowed Maliki a second term.
Iraqiya joined a unity coalition headed by Maliki, winning posts such as the parliament speakership, one of three vice president posts and the finance ministry. Shi'ites took the prime minister's office and Kurds the presidency.
But since then Iraqiya says Maliki has failed to live up to power-sharing agreements, including the formation of a strategic policy council post for Iraqiya leader Iyad Allawi, who like Hashemi, is a bitter rival of Maliki.
At least nine times over the last year, candidates for the Iraqi defence minister post were put forward, but each time they have been rejected or failed to pass the first stage because of mistrust or squabbling.
They call it a partnership government, but these are not partners, they are adversaries, Mahmoud Othman, a veteran Kurdish lawmaker, said shortly before the crisis. This is a failed government.
ARREST OR COLLAPSE?
But Iraqiya has little room to manoeuvre. Without the support of other political blocs like the Kurds or a breakaway Shi'ite group, Iraqiya may find it difficult to walk away from government posts that give it access to political power, and from the 80 seats it holds in the 325-seat parliament.
Shi'ite leaders appear to be betting that divisions within Iraqiya will keep key Sunni figures clinging to their government posts rather than splitting to back Hashemi and trying to scuttle the government.
Even if Iraqiya abandons the government, the constitution would allow the Shi'ite coalition to work with the Kurdish blocs who would more likely join them to form a majority government, Shi'ite lawmakers say.
I do not think the political process will collapse because, Iraqiya is already fragmented, said Sami al-Askari, a senior lawmaker and a close Maliki ally in his State of Law coalition.
Senior Shi'ite leaders say the charges against Hashemi are tied to plots against Maliki. But, they said, Maliki is unlikely to push authorities to execute the Hashemi warrant because of the expected fallout and uncertain Sunni reactions.
We will leave the door open for Iraqiya, but if they tried to stop the political process, we will go ahead without them, one senior Shi'ite lawmaker said. Arresting the vice president politically is a problem.
But the moves against Sunni leaders are a gamble as provincial Sunni officials campaign for more autonomy from a central Shi'ite-led government that some see as disinterested, and bowing to the whims of neighbouring Shi'te power Iran.
Maliki's government recently arrested more than 200 members of Saddam's banned Baathist party, some of whom officials had said were involved in plots against the government. The arrests triggered protests in the Sunni stronghold Anbar province.
Heightened rhetoric could encourage more Sunni-backed protests and push Sunni Islamists to step up attacks on government targets, already in the sights of a stubborn al-Qaeda linked insurgency, said Eurasia's Crispin Hawes.
The clear winners, though, are Iraq's Kurdish blocs who strengthen their bargaining position within the central government, and within semi-autonomous Kurdistan's own disputes with Maliki.
Any attempt to negotiate a majority government or a Sunni split will likely need Kurdish backing within Iraq's central government.
Kurdistan, locked in a struggle over oil and territory with Maliki, may use the crisis as leverage in talks with Baghdad over disputed Kurdistan contracts it has signed with U.S. oil giant Exxon Mobil, which Maliki's central government says are illegal.
Maliki still has a chance of keeping the government together - the Kurds will be critical to this, said Gala Riani at IHS Global Insight. They might use this opportunity to press Maliki for the resolution of long-standing disputes.
(Additional reporting by Suadad al-Salhy in Baghdad)