Without referring specifically to a simmering row over forces for a Nato training mission in Iraq, he also warned on Thursday that the coming months could test the 26-member alliance's unity.
"We all know that consensus does not come by magic and requires both a healthy culture of debate and each ally's sense of responsibility," he said in an opening address to Nato foreign ministers meeting in Brussels.
"We also know the importance of preserving this consensus over the weeks and months ahead of us, as our operations and missions prove costly and difficult.
"This requires a fair burden sharing among allies. It also requires keeping our public opinions on board. And foremost it requires a good transatlantic dialogue and a clear political strategy," he added.
The North Atlantic Treaty Organisation ministers, including US Secretary of State Colin Powell, were notably set to discuss the expansion of the Nato-led International Security Assistance Force (ISAF) peacekeeping mission in Afghanistan.
Nato is also seeking contributions for a new military training operation in Iraq in time for elections scheduled for next month. The alliance wants about 300 instructors for the job.
Expanding the ISAF mission in
Afghanistan will be discussed
Planning for the operation has been bedevilled by discord among allies over the details. A group of countries who were opposed to the Iraq war are notably refusing to send any of their forces to the violence-wracked country.
A senior official called the row a "serious disagreement" on the eve of the Brussels talks, although Nato officials have sought to downplay the prospect of open clashes over the issue.
Meanwhile, US President George Bush is expected in Brussels on 22 February to meet Nato and European Union leaders, a German foreign ministry spokesman said on Thursday.
German Foreign Minister Joschka "welcomes the ... visit which means a chance for a new transatlantic consensus", said ministry spokesman Walter Lindner.
But officials accompanying Powell said they could not confirm the date, noting that the White House was responsible for Bush's travel arrangements.