Nato ambassadors have unanimously agreed to help Poland in peacekeeping operations in Iraq.
Robertson: Nato will give Poland advice as soon as possible
The plans involve some technical assistance but as yet no direct presence of Nato troops on the ground.
The BBC's Tim Franks in Brussels says that although Nato's help is modest, the decision is symbolically important and will provide a welcome balm for sore feelings left by the war.
United States ambassador to Nato Nick Burns welcomed the decision, saying the alliance could play an even bigger role in Iraq in the future.
"It will allow Nato to play the role that we think this alliance is designed to play," he said.
"There's no question that Nato is out on the front lines in the global war on terrorism."
Earlier this month Washington asked Warsaw to take over military administration in central Iraq in recognition of Poland's role in the US-led military action.
We're not talking about a Nato presence in Iraq, we're talking purely and simply about Nato help to Poland
Nato secretary general
In February French President Jacques Chirac berated Poland, among others, for its support for the US action.
However, French officials said on Wednesday that Paris had no objection to helping the Polish operation.
Nato military experts will go to Warsaw later this week to find out what Poland needs to run its sector.
The alliance has agreed to share intelligence and provide logistics - but though the operation will not for the moment be run by Nato full-time.
"We're not talking about a Nato presence in Iraq," Secretary General George Robertson said. "We're talking purely and simply about Nato help to Poland."
Lord Robertson gave no timetable for the planning, but said it would be done as soon as possible.
Military experts will first liaise with the Poles to find out what they need.
Poland is still well short of the full number of soldiers it will need.
At least 7,000 troops are needed to patrol the sector, situated between a US-controlled zone to the north and the British-controlled south.
Warsaw will host a meeting of countries willing to join the operation on 22-23 May.