The Obama administration is moving ahead with the sale of nearly $US11 billion worth of arms and training for the Iraqi military, despite concerns Prime Minister Nuri al-Maliki is consolidating his authority in a one-party Shiite-dominated state and abandoning the US-backed power-sharing government.
The military aid, including advanced fighter jets and battle tanks, is meant to help the Iraqi government protect its borders and rebuild a military that before the 1991 Persian Gulf war was one of the largest in the world.
But the sales of the weapons - some of which have already been delivered - are moving ahead even though Mr Maliki has failed to carry out an agreement that would have limited his ability to marginalise the Sunnis and turn the military into a sectarian force.
While the US is eager to beef up Iraq's military, at least in part as a hedge against Iranian influence, there are also fears that the move could backfire if the Baghdad government ultimately aligns more closely with the Shiite theocracy in Tehran than with Washington.
US diplomats, including ambassador James Jeffrey, have privately expressed concern about the military relationship with Iraq, saying that it could have political ramifications for the Obama administration. There is growing concern that Mr Maliki's apparent efforts to marginalise the country's Sunni minority could set off a civil war.
The program to arm the military is being led by the US Embassy in Baghdad , which, through its Office of Security Cooperation, serves as a broker between the Iraqi government and defence contractors like Lockheed Martin and Raytheon. Among the big-ticket items being sold to Iraq are F-16 fighter jets, M1A1 Abrams main battle tanks, cannons and armoured personnel carriers. The Iraqis have also body armour, helmets, ammunition trailers and sport utility vehicles, which critics say can be used by domestic security services to help Mr Maliki consolidate power.
''The purpose of these arrangements is to assist the Iraqis' ability to defend their sovereignty against foreign security threats,'' said Captain John Kirby, a Pentagon spokesman in Washington.
But some Iraqi politicians and analysts, while acknowledging US military withdrawal had left Iraq's borders and airspace vulnerable, cited many reasons for concern.
Despite pronouncements from US and Iraqi officials that the Iraqi military is a non-sectarian force, they said, it had evolved into a hodgepodge of Shiite militias more interested in marginalising the Sunnis than protecting the country's sovereignty. Across the country, they said, Shiite flags - not Iraq's national flag - fluttered from tanks and military vehicles, evidence of the troops' sectarian allegiances.
''It is very risky to arm a sectarian army,'' said Rafie al-Essawi, the country's finance minister and a leading Sunni politician. ''It is very risky with all the sacrifices we've made, with all the budget to be spent, with all the support of America - at the end of the day, the result will be a formal militia army.''
Mr Essawi said he was concerned about how the weapons would be used if political tension led to renewed sectarian violence. Some Iraqis and analysts said the weapons could give Mr Maliki an advantage in preventing Sunni provinces from declaring autonomy from the central government.
''Washington took the decision to build up Iraq as a counterweight to Iran through close military co-operation and the sale of major weapon systems,'' said Joost Hiltermann, the International Crisis Group's deputy program director for the Middle East.
''Maliki has shown a troubling inclination toward enhancing his control over the country's institutions without accepting any significant checks and balances.''
Uncertainty over Mr Maliki's intentions, and with that the wisdom of the weapons sale, began to emerge even before the last US combat forces withdrew 12 days ago. Mr Maliki moved against Sunni rivals, arresting hundreds of former Baath Party members on charges they were involved in a coup plot.
Then security forces under Mr Maliki's control issued an arrest warrant for the country's Sunni vice-president, who fled to the semiautonomous Kurdish north.
The Americans warned Iraqi officials that if they wanted to continue receiving military aid, Mr Maliki had to fulfil a 2010 agreement that required the Sunni bloc in parliament to have a say in who ran defence and interior ministries.
But despite a pledge to do so, the ministries remain under Mr Maliki's control, angering many Sunnis.