A number of EU leaders have stated that their joint defence policy must not compete with Nato's, two days after a US diplomat described the policy as a "threat to Nato's future"
Berlusconi: Foreign ministers will be obliged to agree on 28 November
The Belgian, British and Italian prime ministers, and the French president all insisted that EU defence plans were designed to complement Nato.
The Italian Prime Minister, Silvio Berlusconi, whose country holds the EU's rotating presidency, said US fears on the subject should be allayed.
"I do not think there will be such misunderstandings in future," he said at the end of a two-day EU summit in Brussels.
Nato ambassadors are to hold a special meeting on Monday at Washington's request to discuss the EU plans.
The US position is hardening just as the UK has been relaxing its opposition to plans - drawn up by France, Germany, Belgium and Luxembourg in April - for a separate EU military command.
UK Prime Minister Tony Blair, said on Friday that he would never put Nato at risk and that he was pressing for Nato's pre-eminence to be clearly established in the future EU constitution.
"It is ambiguous at the moment," he said.
But he added that it was important that Europe had the capability to act independently "where America for one reason or another doesn't want to be involved".
French President Jacques Chirac said Europe's defence capability should be "completely consistent with our Nato commitments".
Belgian Prime Minister Guy Verhofstadt said: "We have to be very clear on what we are saying: European defense will not compete with Nato."
The leaders were reported to have narrowed their differences over proposals for closer military co-operation by a vanguard of EU states.
EU security chief Javier Solana described this as a "good thing" provided that all EU states were able to set defence policy - just as all states, including those outside the eurozone, set EU economic policy.
There was no progress in resolving other key disagreements over the constitution - such as the issue of national voting weights and the number of commissioners.
In other key decisions:
- Leaders said they would decide at their December summit on a "quick start programme" of projects that would boost growth in the European economy. They said Europe was undergoing a fragile economic recovery that would pick up in 2004.
- They dropped plans for the EU to set quotas for the number of immigrants each member state should take in, but agreed to work together to beef up immigration controls on the EU's external borders
- They called for a "realistic schedule" for the handover of power in Iraq, and a "strong role" for the United Nations. They also said they would actively help drum up money for Iraq at a donors' conference in Madrid next week.
- They demanded that the Palestinian Authority bring to justice the bombers who killed three Americans in the Gaza strip, and place all security services under the control of Prime Minister Ahmed Qureia
- They said Iran must agree to surprise UN inspections of its nuclear facilities
- They called on Serbia and Kosovo to continue efforts to resolve their differences.
In Friday's final session, French President Jacques Chirac represented German Chancellor Gerhard Schroeder, who had to return home for a crucial parliamentary vote.
"It was a sign of confidence and friendship which I found particularly touching, so I just limited myself, at his request, to making the comments I was asked to make in Germany's name," Mr Chirac told reporters.
"It so happened that his comments were identical to those that France wanted to make anyway."
The failure to make progress in discussions on the constitution raised doubts about the chances of reaching agreement on a final text by the mid-December deadline.
Swedish Prime Minister Goran Persson said he thought next year's Irish EU presidency would have to continue the consultations.
"This morning has not taken it all in any way forward," he said on Thursday.
But Mr Berlusconi nonetheless predicted agreement before the end of the year on a document which would be "good for the
planet, good for democracy, good for liberty and good for our values".
He said a meeting of EU foreign ministers on 28 November would be the time for
compromise - and no-one would be allowed to leave until there was a positive result.