So far, the West has done reasonably well containing terrorist threats. A year ago Osama bin Laden had a very elaborate plan to cause trouble in various places across the planet, but he was mainly stopped. The high level of vigilance in the West against this threat seems to have paid off.

For now, the main threat still seems to come from political Islamists. But terrorism is the weapon of the weak, so undoubtedly other groups will emerge in the future.

Communications and travel links strengthened by the globalization process make it easier for transnational networks, from terrorist to mafias, to operate. Globalization spreads disorder through the same kind of links that enable the expansion of legitimate commerce and other legal activities. And a good part of the world today is covered by zones of disorder, from Colombia to the Caucasus.

Migration is the central issue of our time. In the developed world there is an aging and, soon, shrinking population. In the larger part of the rest of the world a population expansion continues, generating a mainly youthful population that is the source of migration, instability and terrorism.

Europe and Japan will face the greatest challenges in coming to grips with this reality. The fertility rate in much of Europe is headed down to 1.2; in Japan it is about 1.3. Facing aging and declining populations, these countries will not be able to sustain themselves economically without opening up to larger and larger numbers of immigrants something they are not accustomed to. This is particularly true of Japan. For them to open up their doors to immigrants will require a social revolution.

European countries have had a bit more experience, but the pressures have already set off xenophobic reactions. Their dilemma is that if they want to maintain the cultural integrity of their countries, they must limit or stop immigration; but they can't, because of the economic necessity. If they admit migrants without assimilating them into the culture, then they will be faced with huge pockets, as in Frankfurt or Berlin, of disconnected and disaffected foreigners.

These countries have little experience assimilating people from a very different culture. Moreover, many immigrants now don't want to be assimilated. With advances in travel and communications, one can remain a Turk while living in Germany.

America is facing the same challenge as the rest. The factors that made assimilation work in the past waves of immigration in the mid-19th century and just before World War I are no longer present.

Then, both waves of immigration ended, aiding assimilation as no more of the same kind of people came. Immigrants came from very diverse sources, from Italy to Ireland to Poland to Greece to China. When the immigrants arrived in the United States they dispersed across the country.

The current wave of immigration to the United States is an endless stream, much of it illegal. It is overwhelmingly Hispanic, and within that primarily Mexican. And it is concentrated in the Southwest, Texas and California.

In the first waves of immigration there were two categories: the "converts," who wanted to be assimilated and went over completely to the American way of life, leaving their language and native habits behind, and the "sojourners," who worked in America for, say, 15 years and went back home to Sicily and lived well.

Now immigrants are neither converts nor sojourners. They go back and forth between California and Mexico, maintaining dual identities and encouraging family members to join them. Mexican presidential candidates now campaign for votes and money in Los Angeles.

So the United States has to face a whole complex of issues here, just like Europe and Japan. It cannot assume that because it was successful at assimilation in the past it will be in the future.

Quote: "The principal responsibility of Western leaders is not to attempt to reshape other civilizations in the image of the West, which is beyond their declining power, but to preserve, protect and renew the unique qualities of Western civilization."

- Samuel P. Huntington in The Clash of Civilizations and the Remaking of World Order