ใใ remains the most compelling general framework for understanding international relations. States continue to pay close attention to the balance of power and to worry about the possibility of major conflict. Among other things, this enduring preoccupation with power and security explains why many Asians and Europeans are now eager to preserve – and possibly expand – the U.S. military presence in their regions. As Czech president Vaclav Havel has warned, if NATO fails to expand, “we might be heading for a new global catastrophe...[which] could cost us all much more than the two world wars.” These are not the words of a man who believes that great power rivalry has been banished forever.