Nato has opened a new training centre for Iraqi forces in the heavily-guarded Green Zone in the centre of Baghdad.
Training new Iraqi troops has been a priority for the US-led coalition
Secretary-General Jaap de Hoop Scheffer - who spoke at the inauguration - said 100 Iraqi officers would be trained at the centre by the end of the year.
Washington has been pushing Nato to take on a bigger role in Iraq.
Meanwhile, UN officials urged countries with Iraqi asylum seekers not to send them home, warning that most of Iraq is as dangerous as it was a year ago.
It was a rare visit by Nato's top brass to Baghdad to hoist their flag over the long-awaited training academy, correspondents said.
"This centre makes and marks a significant step toward a more secure Iraq," Mr Scheffer said.
He was accompanied on his trip by the alliance's supreme commander for operations US Gen James L Jones.
A recent report by a prominent US analyst said Washington should accept that Nato would not provide training on the required scale.
Because of French and German opposition to a wider role in Iraq, the organisation has limited itself to training and equipping some Iraqi forces.
The UN High Commission for Refugees said in its report on Iraq that the authorities were still not able to protect civilians in southern and central areas from violent attacks.
The report said the security situation had deteriorated in many places and the government could not provide people there with the basic services needed for a secure and stable life.
The UN refugee agency says security has improved in the three Kurdish-controlled northern provinces - Sulaimaniya, Dohuk and Irbil.
However, there has been no improvement in most areas over the last year, while some other parts of Iraq was actually more dangerous, its report says.