The Foreign Secretary stressed that the Kosovo crisis had shown that Britain could make a "leading contribution" on the basis of building "new partnerships".
He told MPs during resumed debate on the Queen's Speech: "We must absorb the lessons of Kosovo and ensure that European armed forces have the rapid, flexible and mobile capacity necessary for crisis intervention.
"The European members of Nato should have the capacity to conduct crisis management where the Alliance as a whole is not engaged. And an increased capacity to contribute by Europe will be welcomed by America."
Mr Cook's remarks came as large gaps in Europe's defence capability were due to be exposed in a Western European Union audit report tomorrow.
The report, which could lead to demands for a big increase in European Union (EU) defence spending, will show that Europe needs more aircraft carriers and "heavy lift" freight planes to fulfil long-term plans for a European defence arm to carry out a policing role beyond its borders.
British defence ministers will today outlineplans to build a new aircraft carrier in Britain and the RAF is planning for new heavy lift aircraft.
The development of a European defence arm will move a step further with a meeting at Downing Street on Thursday of Tony Blair and Lionel Jospin, the French Prime Minister.
The EU Helsinki summit next month is expected to set up a new EU defence committee to oversee defence co-operation in Europe. Defence and foreign office sources said it would not be run by the Commission or Parliament; EU action will require unanimity by the 15 EU partners.
The sources also denied there was any intention to create a European standing army. They admitted there were doubts in the United States about the possibility of a hidden agenda to set up a rival to Nato. But, opening debate in the Commons, Mr Cook insisted: "Our security initiative is not about the defence of the continent. That remains squarely the responsibility of Nato."
The Foreign Secretary said that the appointment of Lord Robertson, the former defence secretary, as Secretary General of Nato, left the Government "even better placed to make sure that Europe and the North Atlantic Alliance work together for a free and secure Europe".
He added: "It is on the basis of our successful record of building new partnerships and strengthening old alliances that this Government is making Britain a leading player in Europe and a respected force for good around the world."
But, Iain Duncan Smith, the shadow secretary for defence, attacked the concept of a European defence arm as "fatally flawed". "The concept of a European army endangers our special relationship with Nato. This policy is not defence driven but driven by the political aspirations of the Prime Minister.
"This policy has been drawn up by the same people that gave us the Common Agricultural Policy. It is fundamentally flawed," he said.Reuse content