The one-day meeting of defence ministers, also attended by Russia's Sergei Ivanov, reaffirmed its support for the US, which blames Saudi-born militant Osama Bin Laden for the 11 September attacks on the World Trade Center and the Pentagon.
Mr Wolfowitz had given what he called a full briefing, he said at a news conference later. But he stressed that no decisions had been taken.
Lord Robertson added that the US had so far made no request for military action from Nato.
Mr Wolfowitz made it clear that a lengthy struggle was in prospect, with the military option only one element in that struggle, officials said.
But, contrary to expectations, evidence supporting the US view that this was an attack from abroad does not appear to have been provided, or asked for.
Under the terms of the Nato treaty, attacks initiated from abroad count as assaults on the entire alliance, justifying a collective response.
The BBC's Justin Webb in Brussels says that at this stage Nato's involvement seems very much one of background support.
In other developments:
Russian contacts
American diplomats are saying the sharing of intelligence and broad support is what they want from Nato at the moment.
Click here for map of possible targets
US Defence Secretary Donald Rumsfeld has said there will be no single co-ordinated assault at the start of President George Bush's fight against global terrorism.
Mr Rumsfeld said the campaign would be long, difficult, and dangerous, and more lives might be lost.
Targeting Taleban
And US President George Bush stressed that the US wanted action against the ruling Taleban, not the Afghan people.
"The mission is to root out terrorists, to find them and bring them to justice.
"And the best way to do that, and one way to do that, is to ask for the co-operation of citizens within Afghanistan who may be tired of having the Taleban in place."
In a message to the American people, the Taleban leader, Mullah Mohammad Omar, accused the United States of committing "atrocities" against the Muslim world.
"The American people must know that the sad events that took place recently were the result of their government's wrong policies," he said.
Afghans' plight
Up to 20,000 Afghan refugees are stuck in worsening conditions on the border with Pakistan, which is refusing to let them in.
The United Nations is gearing up to cope with up to a million Afghan refugees flooding into Pakistan in the event of an attack by the US-led coalition.
There are an estimated 3.5 million Afghan refugees already living in Iran and Pakistan and at least a million more displaced inside Afghanistan.
Afghan refugee crisis
UN fears 300,000 people may run out of food by end of week
Up to 20,000 massed on Pakistan border
UN surveying 75 possible sites in Pakistan for new refugee camps
About 3.5 million refugees already live in Iran and Pakistan - at least a million more displaced in Afghanistan
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