Officials said France, Germany, Italy and Spain had agreed to remove restrictions on aiding other countries' militaries in an emergency in Afghanistan. But the four nations will not be sending troops to regularly fight alongside the British, Canadian, Dutch and American forces on the front lines of battles with the resurgent Taliban in the south and east.
"The summit did not have the character of a major breakthrough," Polish President Lech Kaczynski said. "Not all countries showed the same level of determination."
British Prime Minister Tony Blair tried to cast the summit in a more positive light.
"These have been significant steps in the right direction," Blair said. "Have we got absolutely everything we wanted? Not yet."
NATO leaders pledged in a closing statement to stay the course in Afghanistan. Blair said it was crucial that they had agreed that the alliance must succeed.
NATO officials said they received assurances at the leaders' dinner Tuesday night that all nations would allow their troops in the 32,800-strong allied Afghanistan stabilization force in the nation to come to the aid of allied units in trouble anywhere in the country.
Officials said at least three nations, which they did not name, offered to send more troops.
President Jacques Chirac said France planned to send more helicopters and warplanes. French officials said he would also allow troops to operate beyond their base in Kabul, the Afghan capital, when needed.
"There should be no doubt on our common determination to make a success of this mission," French officials quoted Chirac saying at the meeting. "In support and solidarity with our allies, France has decided to strengthen its contingent."
Nations with troops in the south and east have raised concern that limits on troop deployments risk undermining alliance solidarity and public support for the mission, while only some allies are taking most casualties.
"Losing young men and women is the surest way that can happen," Canada's Foreign Minister Peter MacKay said. Progress "can still be eroded ... if you have people coming home in coffins," he said.
Canada has suffered 44 fatalities in Afghanistan — 36 this year alone. Most occurred after NATO troops moved into the south this summer.
Leaders at the summit also declared that a new 25,000-member rapid-response force designed as the spearhead of a modernized NATO military is ready for action after four years of preparation.