Terrorism isn’t a 20th-century phenomenon, but the circumstances of September 11—the way al Qaeda organised and funded itself and conducted its operations—could only have come out of the globalising world of the 1990s.

That decade began with one of the 20th century’s most unanticipated events, the collapse of the Soviet Union and the crumbling of the Cold War structures that had shaped global politics.

This is a good place to begin because, however we weigh up the reasons for the fall of the Soviet empire, a central element was economic; the incipient impact of emerging technology that led to a revolution in the cost of transferring information and distributing goods. By driving the opening of markets and the rapid dissemination of data, these brought out starkly the inability of autarkic economies to compete with their rivals, and made closed political systems much harder to sustain.

Such changes—the growth of the internet and mobile communications especially—dominated the 1990s. They led to a greater integration of international and domestic economic policy than the world had seen before, a fusing of the external and internal economies.

The disappearance of the barriers between the Cold War blocs of East and West gave a new vitality to regionalism, enabling the EU to expand, ASEAN to embrace Indochina and APEC to be formed.

The emerging economies of Asia set themselves up best to benefit from this globalising world. It was the “Time of the Tigers”, and the Asian miracle accelerated, as rapid growth spread from North to Southeast Asia.

The first big challenge to this emerging story came with the Asian financial crisis from July 1997 onwards. In Thailand, South Korea, Malaysia, Singapore, the Philippines and Indonesia, currency links with the US dollar broke under pressure, sharemarkets collapsed and foreign capital fled. In a single year we saw a reversal of capital inflows to Korea and the ASEAN countries on the order of $100 billion.

Asia experienced the worst slowdown in the developing world for thirty years. But it was the political rather than the economic results of that crisis that mattered most for Australia, and shaped our contemporary environment more directly than September 11.

In May 1998, Soeharto’s new order government fell. But contrary to the pundits who predicted the imminent break-up of Indonesia, a more diffuse and decentralised power structure emerged, shaped by an authentically Indonesian democracy.

This reform and democratisation in turn transformed Southeast Asian regional politics and made possible the development of a deeper and more politically sustainable Australia-Indonesia relationship. And in the aftermath of September 11 and the Bali bombings, it would underpin one of the world’s most successful efforts against terrorism.

And the crisis led directly to the independence of East Timor, the final act in the long process of decolonisation in Asia, which had defined so much of Australia’s foreign policy since the end of the World War II; and provided Australia with pre-September 11 experience in stabilising fragile states.

But perhaps most importantly, the crisis consolidated the rise of China. A lesson Beijing had drawn from the fall of the Soviet Union in 1991 was that economic growth was essential for the party’s continuing hold on power. So, during the 1990s, Jiang Zemin and Zhu Rongji drove greater economic openness and pushed forward market-oriented reforms. In 1997 the loss-making network of state-owned enterprises was opened to diversified ownership, and reform of the bloated public service began. In the same year, the private sector was officially described as “an important part of China’s socialist market economy”.

But China’s capital account remained resolutely closed. So when the Asian crisis came, China was insulated from exposure to international financial markets. Its share of Asia’s foreign direct investment had begun to edge up from 1992, but after the crisis, more foreign investors asked themselves why they should fiddle around on the edges when they could go directly to the world’s most populous market. Investment stampeded northwards from Southeast Asia and China’s total stock of foreign direct investment grew to become second only to that of the United States.

By 2001, China was ready to take the most important step towards its integration with the global economy by joining the World Trade Organisation. Just months before its accession, and facilitated by the same technology which made China’s growth possible, al Qaeda terrorists attacked the World Trade Centre. So globalisation’s two sides—dark and light—were brought into sharp focus.

The 9/11 attacks shook to its core the confidence the US felt in its traditional security between the moats of two great oceans. The world that changed after September 11 was principally the world as the United States felt it to be; and to that perception in varying degrees the world had to adjust.

Threats from radical Islamist terrorist groups against American targets, and even on American soil, weren’t new. Important sections of the national security administration of the United States had been focusing on them during the 1990s. But the World Trade Centre and Pentagon atrocities moved the issue to the very centre of American thought.

For the first time since the Cuban missile crisis, there was an urgent weighing-up of the possibility of some nightmare scenario—not just the prospect of more big terrorist attacks, but the potential use of weapons of mass destruction, even of crude nuclear-explosive devices.

The sense of vulnerability and anger sparked by September 11 made the US much more ready to act against threats to the US homeland and to US global interests.       For many Americans, this was worse than Pearl Harbour: an attack on the core symbols of the US economy and government.

The US response answered dramatically the question which had been unresolved since the end of the Cold War of what American grand strategy would be. The “post-Cold War” hiatus was over. The war on terror had begun.

In September 2002, President Bush outlined a National Security Strategy of exceptional ambition. It brought together a series of themes he had spoken about since the attacks on the American homeland, beginning with the belief that “the 20th century ended with a single surviving model of human progress”: freedom, democracy and free enterprise. America’s actions in confronting terrorists and tyrants were not to be undertaken for unilateral gain, but to create “a balance of power that favors freedom”. The terrorist attacks of September 11 had provided a moment of opportunity for the US to “extend the benefits of freedom across the globe”.

That required US power, and it was the goal of the United States, in the president’s words, “to build and maintain our defences beyond challenge … Our forces will be strong enough to dissuade potential adversaries from pursuing a military build-up in hopes of surpassing or equalling, the power of the United States”.

Pre-emptive action would be necessary to prevent the use of WMD by terrorists, as would national missile defence and cooperation with other states on non-proliferation. A common threat would help to bind all the great powers of the world for the first time.

Australia’s response to September 11 was heavily shaped by the coincidental presence in Washington on that day of the prime minister John Howard. The force of his response to the disaster and the first-hand understanding it gave senior Australian policy makers of the impact of the catastrophe, set the scene for a deeper political, security and economic relationship with our major ally.

The ANZUS alliance was invoked for the first time—and remains the basis for our engagement in Afghanistan. Australia was also an early participant in Iraq in 2003. These military commitments, helped by the personal closeness of Bush and Howard, intensified Australia-United States security integration. There is no doubt they also helped congressional passage of the US-Australia Free Trade Agreement.

After the 2002 Bali bombings—killing 202 people, 88 of them Australian—Australia’s regional relationships took on more of the dimensions of the emerging, post-September 11 transnational agenda.

It was understood by then that borders that were increasingly permeable to trade and tourism were also open to threats ranging from terrorists to money launderers, from nuclear proliferators like Pakistan’s Abdul Qadeer Khan to pathogens like the SARS virus.

Counter-terrorism co-operation was an important element in bringing Australia closer to newly democratic Indonesia. Indonesia’s successful prosecution of more than 470 terrorism suspects in public and transparent trials was a major achievement of the counterterrorism effort, and has been a key factor in turning Indonesian public sentiment against terrorism. But other aspects of the transnational agenda such as the Bali processes on people smuggling were also engaged.

One lesson we drew from September 11 and from al Qaeda’s operations in Afghanistan was that if you let problems fester they could become major international security threats. The mode of the time was interventionist.

IF the 10 years before September 11 were marked by the merging of domestic and foreign economic policy, in the decade afterwards it was the amalgamating of domestic and foreign security policy that mattered.

We’ve lived through what will be seen in retrospect as the “national security” decade—a period in which most governments, including Australia’s, revised fundamentally their ideas of what national security is, who is responsible for it, and how it is done.

The national security decade probably came to an end with the global financial crisis in 2007 and 2008. It was overtaken by politics and economics. Domestic political calculations changed. Interventions turned out to be harder to bring off than we hoped and fiscal pressures on many of the countries involved—even the biggest—began to build.

For example, US government expenditure on homeland security alone has risen by $580 billion over 2001, while Australia has spent about $2 billion on the regional assistance mission to Solomon Islands.

 It’s not that security won’t continue to be centrally important to governments or that the lessons we have learnt about how to manage it in a more comprehensive way will be lost, but from now on, we’ll be talking about it in different ways. And tightening budget constraints will force governments to get better at setting priorities and evaluating effectiveness.

A decade on from September 11, there are three lessons that remain with us.

One is that all international policy rests finally on a sense of security on the part of our citizens. Terrorists can destroy that sense of security quickly and no government can afford to let down its guard.

Osama bin Laden’s death is an ending of sorts, but not a neat one. New forms of terrorism—some not from groups but from self-radicalised individuals—will grow. The trail won’t end but will wind and fork in different directions, testing our counterterrorism measures.

So while the global financial crisis and the end of the national security decade mean that things will be done in different ways, visions of the twin towers and of Bali will continue to shape the memories and actions of governments and people. We won’t go back to a pre-September 11 world.

Second, distance still means less than it did in the 20th century. The attacks of September 11 were planned from afar and co-ordinated across continents. Cyber threats can emanate from anywhere. Fragile states and ungoverned spaces still need to be watched and tended. From places like Yemen and Somalia new threats can emerge, including to Australia.

One question for the next decade will be who does the watching and the tending. Among the states of the international system, the competition may be less over who acts to shape the global environment than who manages to avoid bearing the cost of doing so.

Finally, September 11 teaches again a very old lesson. We need to be alert to new and emerging sources of power and influence in the international system. As in the past, our failure to anticipate future change will usually turn out to be a failure of imagination.

For example, we have just seen the unexpected power of social media in the Middle East. And we are at the very earliest stages of understanding all the aspects of cyber power and its place in statecraft.

Those of us who have worked for any time in the field of international policy analysis know that we are grappling with a messy, contingent environment shaped by human agency and natural catastrophe, slow-moving trends and sudden impulses, technology, sociology, demography; all acting together in an often bewilderingly complicated way.

Yet few of us can resist the desire to impose on this random world the comfort of patterns. Such patterns aren’t always analytically sustainable but we cling to them because they’re the best way we know of making sense of the world.

This essay was adapted from a speech the author gave at the United States Studies Centre's September 11 national summit in Sydney in June 2011.