Since the September 11th terrorist attacks on the United States, many people have said the world has changed. If so, has the United States changed with it? The war on terrorism has brought a military response, but some say more innovative approaches are needed to deal with terrorist methods.

Thomas Homer-Dixon is director of the Center for the Study of Peace and Conflict at the University of Toronto. He spoke to VOA English to Africa reporter Joe De Capua about how the world has changed since 9/11. The associate professor of political science says the United States has retreated to fairly conventional security responses to the attacks.

He says the US must adapt to the mortal threat of terrorism, which he describes as ?constantly shifting and dynamic.? He says, ?The terrorists are using western technology against the west, technology of communication, technology of destruction.?

Professor Homer-Dixon says, ?There must be a more profound recognition on the part of decision makers of the extraordinary complexity of the world.? He says this not only includes security threats, but also ecological and economic and epidemiological threats, such as HIV/AIDS. He says these are ?complex interlinked problems.?

He recommends the United States not view the problems separately and seek help from friendly nations rather than going it alone.