Nato opens way for joint response to attacks on US

The Alliance

Nato entered unchartered territory last night by invoking the alliance's cornerstone agreement for collective defence for the first time in its history, opening the way for an international military response to the carnage in the United States.

An unprecedented declaration agreed by all 19 alliance states said the deadly terrorist strikes in New York and Washington might have to be regarded as an attack on all Nato members.

Lord Robertson of Port Ellen, the Nato secretary general, said: "The [North Atlantic] Council agreed that if it is determined that this was an attack directed from abroad against the United States, it shall be regarded as an action covered by Article Five of the Washington Treaty, which states that an attack against one ally is an attack against them all."

The practical implications of the tough Nato stance remained unclear, although an alliance source described it as a "massive political message" of intent to the perpetrators of the attacks – and a demonstration of solidarity with the victims.

Nato officials said that the communique does not give a clear commitment to assist any US retaliation – certainly not before America has identified the culprits and proposed a course of action. Washington will not be handed a "blank cheque", said one source who added that any decision to launch joint strikes would require further Nato deliberation, as would a decision to place national forces under alliance command.

However, the decision provides a big gesture of support to the US, raising the prospect of the entire alliance backing any US counter-measures.

In reality last night's move leaves open two possibilities: the US could retaliate unilaterally (or perhaps with allies such as the UK), avoiding the risk of security lapses by avoiding wide consultation; alternatively, it could now go with confidence to Nato and call on all 18 other states to back US strikes or a broader strategy – perhaps including sanctions. Lord Robertson said no military plans had been discussed. "The country that is attacked has got to make the decision and has got to be the one that asks for help. They have not reached that judgement as to who did it and why they did it," he said.

The Italian Foreign Minister, Renato Ruggiero, said in Brussels that "an attack on the US territory is an attack on the values that belong to all of us" and Germany, the UK and Canada all backed a tough declaration.

The move was seen as an historic one inside Nato's headquarters in Brussels, where ambassadors held three emergency meetings.

Under the collective security arrangement in article five of the North Atlantic Treaty of 1949, an armed attack on one member by another state is considered an attack against the alliance and its members would help each other. That would bind them to "assist the party or parties so attacked by taking forthwith, individually and in concert with the other parties, such action as it deems necessary, including the use of armed force, to restore and maintain the security of the North Atlantic area".

Although Nato countries have been involved in conflicts before, including Britain's Falkands War, the article has never been used before.

And, while President George Bush has spoken of the US being at war, this is a markedly different situation than that envisaged by the alliance's founders. Their preoccupation was an invasion of Nato territory by Soviet forces.

While terrorism was defined as a threat at Nato's Washington summit in 1999, no specific link was made to Article 5.

By implication a reference to collective security would bind all 18 US allies to any retaliatory action taken by American armed forces, though without an obligation to take part in operations. "It is a pretty serious turn of events," said one official, arguing that any ally which then disassociated itself from a US counterstrike would face the question of how they could remain within Nato.