"Bush set out, persuasively, the case for what America sees as its right and duty to declare war against those who attacked it."

For the past 11 days, the world has waited anxiously for America's response to the campaign of terror against it.

Yesterday, US President George W.Bush, in the most important speech by an American leader since World War II, laid down the blueprint for the superpower's counter-offensive.

The hunt for Osama bin Laden is under way. As for state sponsors of terrorism, the warning could not have been more explicit: "From this day forward, any nation that continues to harbor or support terrorism will be regarded by the United States as a hostile regime."

As expected, the President did not shed light on the precise nature of the military tactics the US is planning to adopt. But Bush provided enough broad guidance on the scope and scale of Operation Infinite Justice to build confidence among allies in the West and elsewhere that the US understands the awesome nature of the task it faces, militarily, strategically and diplomatically, before embarking on what shapes as a long and difficult conflict.

The message to an American people impatient for Washington's response was that the engines were primed. "The hour is coming when America will act," the President said.

The message for the Middle East was that the US was not prepared to see moderate governments toppled through a campaign of destabilisation by Islamic extremists: "They stand against us because we stand in their way."

The message to one billion Muslims was that the US respected the teachings of Islam as peaceful: "Those who commit evil in the name of Allah blaspheme the name of Allah." And the message to nations offering a haven to terrorists was choose now or be regarded as an enemy.

For Afghanistan's Taliban regime there was a blunt ultimatum: hand over all terrorist leaders, release and protect all foreign nationals, close every terrorist training camp, and give the US access to the camps to ensure they are no longer functional. Ominously, Bush added: "They will hand over the terrorists or they will share in their fate."

For 10 days after the terrorist attacks, Bush had done no more than nominate bin Laden's network as the "prime suspect" for the assaults on New York and Washington. Yesterday he insisted all evidence pointed to al Qaeda as the culprit.

The terrorist cells, he said, operated in more than 60 countries. He argued their aim was to overthrow governments in Egypt, Saudi Arabia and Jordan, to drive Israel out of the Middle East, and to eliminate Western influence in vast regions of Asia and Africa.

"We've seen their kind before," Bush added. Equating the campaign of terror with the fascism, Nazism and totalitarianism of the 20th century, he gave a spirited warning: "They will follow that path all the way to where it ends - in history's unmarked grave of discarded lies."

But how exactly to wage this fight?

Here, Bush sought to modify expectations. This would not be like the Gulf War, he said, nor the air war above Kosovo. An end would not come swiftly. There would be covert operations.

Here, he identified the importance of a global coalition that extended to police forces, banks, and intelligence agencies.

The detail of US strategy will unfold in the weeks to come. Much of what is asked of other governments will be visible only to those in the secure surrounds of cabinet rooms and military headquarters. Such is the nature of a battle to be fought largely in the shadows.

The task for George W. Bush yesterday was to give explanations for why this is happening, and reasons for what lies ahead. He set out, persuasively, the case for what America sees as its right and duty to declare war against those who attacked it.

Tony Parkinson is the international editor of The Age.