No audible thunder preceded September 11, but we were struck by lightning nevertheless - electrified, horrified, and galvanized into action. Now it's adrenaline time and the country wants answers. These are the questions. How is it that radical Islamic sects can send their terrorists to the United States where they use false identity documents, over stay visas, receive advanced degrees in weapons technology, train to be pilots, travel about recruiting new members, and raise funds for their cause? The ease with which these things can happen has been thoroughly documented in two expert reports, one written before the disaster, and one released on October 4. But the question that gets to the heart of the matter was asked by former State Department official Lindsey Grant several years ago Why do opponents of effective border control have so much influence? On January 25, 2000, terrorism expert Steve Emerson warned the House Subcommittee on Immigration and Claims that most Islamic terrorist groups had been operating in the United States for a fairly long time. He said these groups often operate "below the radar screen" under the false veneer of being moderate or mainstream; many pose as non-profit foundations. In California there is a terrorist- related group called "Charity without Borders." Another, "The Holy Land Fund for Relief and Development, " raises money in three states. Mr. Emerson listed 15 reasons why terrorist groups were able to gain a foothold and 12 of those reasons were linked to immigration policy and failures in enforcement. They include the ease of border penetration, the giving of visas to students from terrorist-harboring countries, the failure of universities to keep track of foreign students and their spouses, and the ease with which fraudulent documents of every kind can be obtained. On October 4, Phillip Martin, an agricultural economist from UC Davis and Susan Martin, the former Executive Director of the U.S. Commission on Immigration Reform, wrote a summary paper on immigration and terrorism. They pointed out that the 19 hijackers who killed thousands of people had been in the United States from one week to seven years. Sixteen had entered with student or tourist visas, some of which had expired. They were part of the 8.5 million foreign nationals who also entered with seemingly valid visas, one half of whom did not abide by the terms of those visas, one of which was to leave the U.S. within ninety days. So, as you read this, there are over four million people still here who agreed to go home, but did not. Nevertheless 7.1 million new visas were issued in FY2000. This and other evidence shows conclusively that our government does not track the movements of foreign nationals to see if they are in compliance with the terms of their visas; neither do they verify their actual identity. If the names they give are not in a U.S. database already, false names and forged documentation cannot be detected. Another thirty-one million foreigners, who supposedly enter the United States temporarily each year, do so without any visas at all under a "visa waiver" program for twenty-nine countries. Canadians and Mexicans who live in the so-called "border regions" come and go with Border Crossing Cards. Visas are called the "front door" to immigration, but the National Commission on Terrorism, convened in 2000, concluded that despite elaborate immigration laws, we are a country with de facto "open borders." More troubling is that remedies have been persistently blocked by Congress. As far back as 1996 the INS was required to develop an entry-exit system, but the Senate voted three times to repeal it. The reason is the likelihood of slowing both trade and the flow of cheap labor. That is why we have 5,000 border control agents in the U.S. but send 32,000 troops to protect the population of Bosnia. Martin and Martin conclude that terrorism may require a reversal of the ever-increasing opening of borders. It will be resisted, however, because any investments in U.S. security may act as a tax that slows globalization. New Yorker writer Hendrick Hertzberg acknowledges that the global market makes an important assumption, i.e., that most people will behave in their own economic self-interest. Yet he shows some awareness of tribal passions and irrational fanaticism when he says of the 9/11 attack that terrorists "rode the flow of the world's aerial circulatory system like a virus." Thus, in addition to our failure to be vigilant, there was also Bin Laden, that "wild card" of opportunistic malignancy, who seduced the disaffected and imbued them with suicidal resolve. Hitler, too, lusted after the destruction of cities and people. He wanted to destroy Paris (an order that was not carried out by the German Commander in France), level Leningrad and eventually, to demolish all of Germany before the Allied occupation. On 9/11 we witnessed another lethal nexus between maniacal plans and access to the means of carrying them out. While we need to understand and then correct the ways in which Americans became vulnerable to attack, the determination to change will spring from the strength of our ties to the national family. That means growing up. We need to stop lusting after "bargains." We trust that even U.S.-owned global business now appreciates how expensive that cheap immigrant labor the airlines hired as passenger screeners actually turned out to be. Ninety percent of the employees at Dulles Airport were foreign born and earning minimum wage. Fifteen percent were Pakistanis; others were foreign nationals from Africa and the Middle East who had lived in America less than a year. Protecting our borders will not prevent us from being good neighbors, nor from cooperating with others in dealing with transnational problems like the global environment and the health of the oceans. But the size and composition of the U.S. population are local and national issues, and ecologist Garrett Hardin advises us wisely that we need to "de-globalize them." A sustainable future might still be achievable if we move toward a more decentralized world, living side by side in friendly but distinct and self-sufficient societies. We are entering a new time in our national history, advancing from the adolescence of promiscuous openness to the appropriate caution and vigilance that signal our maturity. [The report to the German Marshall Fund of the United States, "Immigration and Terrorism" by Philip Martin and Susan Martin, can be seen on the website www.thesocialcontract.com. A hyperlink to the text appears at the very top of the home page.]