The Nato alliance has confirmed it is to send extra instructors and support troops to Iraq early next year.
Powell is making his last planned trip to Europe as Secretary of State
At a meeting in Brussels Nato foreign ministers agreed to a US request to boost the alliance's training deployment in Iraq from 60 to 300.
New Nato members Poland and Hungary, as well as the Netherlands, were among those who agreed to extra deployments.
But US Secretary of State Colin Powell criticised countries which opposed the Iraq war for not helping the alliance.
However, amid calls for improved ties between the US and Europe, diplomats said President George W Bush will visit Brussels on 22 February next year.
Mr Bush is expected to meet Nato and European Union leaders during what would be the first overseas visit after his inauguration in January.
'Share the burden'
Mr Powell, who will soon stand down as secretary of state, applauded Nato's decision to boost training levels to 300.
But France, Germany, Belgium and Spain and Greece have refused to allow their nationals to take part, even if they are permanently assigned to Nato.
German Foreign Minister Joschka Fischer said before the meeting: "Our position is clear and that is we shall not be sending any troops to Iraq."
The BBC's Jill McGivering in Brussels says the Nato Secretary General Jaap de Hoop Scheffer and Mr Powell expressed frustration, saying that when there is political agreement it should be backed by practical support from all members.
ISAF force in Afghanistan: 8,000 troops, hundreds more wanted
Training mission in Iraq: 60 trainers so far; will rise to 300; plus 1,000 troops in support
But Mr de Hoop Scheffer also described the mission as running "entirely according to schedule".
The Nato training mission in Iraq will initially focus on Baghdad's central "Green Zone" where instructors will train senior Iraqi military staff.
The force will move out of Baghdad in the spring to set up a military academy.
There was disappointment that no agreement was reached on expanding Nato troop commitments in Afghanistan.
The US has offered to place two provincial reconstruction teams (PRTs) under Nato command in the country as long as European Nato allies supply two more such teams, each consisting of a few hundred soldiers and civilian workers.
Mr Powell, on his farewell visit to Europe before standing down from Mr Bush's administration, insisted that the president is genuine about mending ties with Europe during his visit.
The US wants to beef up the Nato presence in Afghanistan
"The president remains committed to the trans-Atlantic relationship," he said.
"The United States and Europe must work in partnership, using our different strengths and abilities to advance the values of freedom and peace."
Foreign ministers in Brussels also discussed the crisis in Ukraine, where presidential elections are to be re-held following claims of widespread fraud.
Nato and Russia issued a joint statement on Thursday backing a free and fair poll.