As President Barack Obama seeks to extricate US troops from Afghanistan - the scene of America's longest war - his administration will soon face another crisis that determines whether US soldiers remain in Iraq. The decision is mostly out of Mr Obama's hands.
Under a security agreement between Washington and Baghdad, the 46,000 US troops still in Iraq are required to leave by December 31. But some Iraqi leaders are pushing for a new agreement that would allow a smaller contingent of US forces to remain beyond the deadline. American commanders argue that Iraqi forces still need help in gathering intelligence and defending the country's borders and airspace.
Prime Minister Nouri Al Maliki has said he will request that US troops remain if a majority of Iraqi lawmakers and political leaders support the idea. But the Iraqi Shiite cleric Muqtada Al Sadr has staked his reputation on forcing US troops out of Iraq.
In late May, Mr Al Sadr's followers staged one of the largest political rallies in Baghdad since the US invasion in 2003. As many as 70,000 supporters gathered in the Sadr City neighbourhood, chanting "No, no, America!" - a message to Iraqi leaders that they should not allow the US to keep troops in the country beyond the end of the year.
The procession was led by thousands of young fighters from the Mahdi Army, Mr Al Sadr's militia which battled US troops for years. Although they were unarmed, the militiamen wore uniforms and marched in disciplined, military formation. This show of force carried another message: Mr Al Sadr is prepared to again unleash his fighters against his Iraqi rivals and US forces if Mr Al Maliki strikes a deal to keep American troops in Iraq.
In January, Mr Al Sadr unexpectedly returned to his home in the southern Iraqi city of Najaf after three years of self-imposed exile in Iran. The cleric had played a role as kingmaker in ending months of political paralysis and securing a second term for Mr Al Maliki as prime minister. Mr Al Sadr also oversaw his movement's transition from a militia force to a powerful political group with 40 seats in Parliament.
More broadly, Mr Al Sadr's recent show of force in Baghdad highlights how unstable Iraq remains and how the political bickering will likely get worse as Iraqi factions debate the future of US troops. He has vowed to withdraw from Mr Al Maliki's government if there is any attempt to keep a US military presence in Iraq beyond 2011. With such a fragile coalition keeping him in power, the prime minister cannot afford to lose the support of Mr Al Sadr's bloc.
While it is focused on popular uprisings throughout the region, the Obama administration has tried to portray Iraq as a success story where democracy is flourishing and violence is under control. But the reality is more complicated. Iraqis have not been able to govern themselves without falling prey to political deadlock, proxy battles and foreign interference.
The security situation around Baghdad is still tenuous, with assassinations and other attacks occurring almost daily. In recent weeks, there has also been an increase in shelling aimed at the American embassy compound in the fortified Green Zone as well as US military bases near Baghdad's airport. On June 6, five US troops were killed by a rocket attack on an American base in eastern Baghdad — the highest single-day death toll for US forces since 2009.
Mr Al Maliki is once again exhibiting his tendency to rule as a strongman: six months after his coalition government was sworn in, he still has not appointed a defence or interior minister. (The prime minster serves as acting defence, interior and national security minister.) Moreover, the large cabinet that includes over 40 ministers has proven unmanageable, while Iraqi political factions are constantly bickering. Leaders meeting behind closed doors make the most important decisions, with little input from the elected parliament.
Many of these problems are rooted in the political jockeying that granted Mr Al Maliki another term as premier. Under pressure from Iran, Mr Al Sadr finally agreed to support Mr Al Maliki's bid for a second term, after Iraq had struggled for nine months with a political vacuum after parliamentary elections in March 2010.
Under the agreement that ended the political standoff, Mr Al Maliki's main rival, Iyad Allawi - a former premier whose coalition won two more seats in the election than Mr Al Maliki's slate - agreed to drop his bid for the prime minister's post. In exchange, Mr Allawi was offered the position of chairman of a new strategic policy council that was supposed to have power over national security and economic matters. But Mr Al Maliki later backed away from creating the council, and Mr Allawi currently has no post in the cabinet.
Many Sunnis accuse Mr Al Maliki - a leader of the Shiite Islamist Dawa party - of trying to exclude Mr Allawi and his Iraqiyya coalition from government. Although Mr Allawi is a Shiite, his secular coalition attracted strong support among the Sunni community in the parliamentary elections. Mr Al Maliki's attempts to exclude Sunnis from power threaten to once again unleash the sectarian warfare that has shattered Iraq. Since he was first appointed as a compromise prime minister in 2006, Mr Al Maliki has failed to appeal to many Iraqis beyond his Shiite Islamist power base.
Against this backdrop of government failures and competing sectarian squabbles, Mr Al Maliki and Mr Al Sadr - uneasy allies who distrust one another - are headed for a new showdown over the fate of US troops. It's a decision that could rupture an already tenuous Iraq.
Mohamad Bazzi is a journalism professor at New York University and an adjunct senior fellow at the Council on Foreign Relations