New tensions over the war, now an entrenched insurgency, cannot be ruled out at the June 28-29 summit, as was recently the case at the G8 meeting, but they will probably not mirror those that divided the Alliance in February last year.
At the time, France, Germany and Belgium opposed the war and initially refused to provide protection for fellow member Turkey should it have come under attack from Iraq, as a warning to the United States and Britain.
Discussions on what role NATO could play are expected to take up much of a working dinner between the 26 heads of state and government on the first day of the summit, according to diplomats.
Until then, representatives from the NATO member states are working overtime in Brussels trying to draw up a draft declaration suitable to all.
"There is no enthusiasm" for a NATO role in Iraq, said one diplomat on condition of anonymity.
Since a UN Security Council resolution was passed on the handover of sovereignty on June 30 from the US-led occupation coalition to a new interim Iraqi government, Washington has been increasingly looking to NATO.
In laying out the summit goals of the United States this month, deputy assistant of state for European and Eurasian Affairs Robert Bradtke said NATO should now study more closely what role it might play.
"Options for a collective NATO role in Iraq could include command of one or more multinational divisions, security for the United Nations, additional assistance to the Polish-led division or training the Iraqi army," he said.
Analysts are pessimistic that the Alliance will go far beyond its current brief of providing largely logistics, transport and communications assistance to Poland.
"I wouldn't expect a major decision in Istanbul," said Daniel Keohane, of the Centre for European Reform in London, but he added: "I wouldn't rule out the Iraqis asking for help in the next six months."
If such a request were to come, "NATO will certainly not slam the door in the face of this interim government, which is fully legitimate," Alliance chief Jaap de Hoop Scheffer told journalists last week.
"The key is in Baghdad," he said, but refused to elaborate on what any future role might entail.
Whatever it is, it will remain relatively modest. Sixteen NATO members already have troops on the ground in Iraq but France and Germany still refuse to contribute to the force.
The Alliance could, as US President George W. Bush has suggested, help train Iraqi security personnel and the new army; an area in which it has considerable expertise.
At the G8 summit, French President Jacques Chirac appeared to leave open that possibility, while affirming that intervention in Iraq was not NATO's job.
Further afield would be the option of taking over the Polish central south sector, or using its AWACS surveillance aircraft to help watch over Iraq's long and porous borders.
In a commentary in the International Herald Tribune on Tuesday, de Hoop Scheffer said he did not wish to prejudge the outcome of talks in Istanbul.
"However it is clear to me that the entire international community has a profound interest in ensuring that the new Iraq finds its feet. The price of failure is simply too high," he said.