Six weeks before an election, there may be a political as well as practical security motive behind the move; the loss of army pay has been a major source of discontent among Saddam's fellow Sunni Arabs, who dominated the officer corps.
Within weeks of Saddam's fall in April 2003, US administrator Paul Bremer disbanded Iraq's 400,000-strong armed forces and security agencies at a stroke.
At the time, US officials said it simply formalised the fact that the army had evaporated in the aftermath of the war, with soldiers deserting en masse.
Now, Washington is racing to build up a new Iraqi army to let it bring home American troops who are pinned down by fighters, many with considerable military experience.
In a statement on Wednesday, issued on the eve of the main annual Muslim holiday of Eid al-Fitr, Defence Minister Saadoun Dulaimi, one of the few Sunnis in government, invited former officers with the ranks of major, captain and lieutenant to return.
"Those who wish to rejoin the new Iraqi army to serve the precious homeland should go to recruitment centres opened around the country ... for medical procedures and interviews," he said, listing six centres around the country where they can register.
The plight of the hundreds of thousands of unemployed former soldiers has been a rallying point for Sunni Arab complaints that the ruling Shia and Kurds are neglecting their interests.
Most of the new army units need
US support to function
After most Sunnis boycotted an election in January, they seem likely to turn out in force at the 15 December ballot. US and Iraqi officials hope this engagement in the political process can undermine popular support for the revolt.
One former major in the air defence corps said he would not serve under the present government or under American command.
"They called us the army of Saddam, but we were the army of the people," said the former soldier, who asked not to be named.
"We were marginalised and neglected at first but they need us now they are in a bad way."
But he added: "I cannot work under the command of the occupiers... I fought them once; how can I possibly serve them?"
Army from scratch
The Shia- and Kurdish-led government has been rebuilding the army from scratch with the help of the US military, and it now boasts more than 100,000 men in around 100 battalions.
Despite the risks, many have joined for the chance of a paid job in a country deep in economic stagnation.
However, many of those units are not yet ready to operate without US support, and many still lack basic equipment such as armoured vehicles to protect them.
In a sign that Iraq's leaders see a further need for US protection until their own troops are trained, the government asked the UN Security Council this week to renew the mandate of the US-led forces for another year after 1 January.