Of course, "dealing with illegal immigrants should be a top priority in the war on terror." That's a no-brainer. Not that most illegal immigrants are terrorists — they aren't. Most are poor, unskilled people who have come to America to work — whether as busboys, farm hands, chambermaids or in some other low-paid, dirty job — and there's rarely any mistaking them for the kind of monsters who sneak into the country to kill Americans. Still, no nation can afford a vast underworld of illicit residents. Not only is this unsafe — a natural haven for real evildoers to hide and thrive in. It also makes a mockery of our democratic principles. And it's more urgent than ever now to do something about it.

The question is what to do. And this is where restrictionists like Mark Krikorian have it wrong. Because the truth is we can't and won't deport even a small share of the foreign workers who do so much to keep our economy running. Nor, in an age of globalization, can we seal ourselves off from the rest of the world. Yes, of course, we can regulate the flow — we must. But we will succeed in doing so only if our regulatory scheme is realistic — if it bears some relation to the number of needed workers who come and go every year.

The best analogy is Prohibition. In the 1920s, we tried and failed to regulate alcohol use. Today, we do so very effectively. But that's because, unlike Prohibition's unrealistic ban, our current regulatory scheme — liquor licenses, blue laws, and the like — bears some relation to people's real habits.

So what, when it comes to immigration, would a realistic regulatory scheme look like? Well, for one thing, it would recognize the reality of the global labor market, acknowledging that more than a million foreigners come to the U.S. each year to work — in jobs we need done, even in a downturn. As is, our ceilings accommodate only about three-quarters of that flow, criminalizing hundreds of thousands of laborers and, in the manner of Prohibition, making it impossible to maintain control of our borders. Surely it would make more sense to regain control over who comes and goes by setting a more realistic ceiling — creating an adequate legal channel for needed workers and, in the process, freeing up resources to focus on the few who truly mean to do us harm? Then the rule of law would have a chance to stick.

So too with the seven million illegal workers already here. The answer isn't a blanket amnesty; no one wants to reward law-breaking. But we do — for our own safety's sake — need to offer these valuable laborers a way in out of the shadows. And the best means to do so would be a gradual scheme under which, over time, they earn legitimacy — by first coming forward and declaring themselves, then paying a fine, and then remaining on the right side of the law, working, paying taxes and assimilating into American life. Earning legal status would take some years, but the security benefits would kick in right away, allowing us to get an immediate handle on who is here and eliminate the vast black market for bogus identity papers.

These proposals may sound counterintuitive, but how would you rather guarantee American security? In the manner of Prohibition — with an unrealistic, unenforceable code? Or with a practical system we can actually implement — one that allows us to track who lives here, who crosses the border, and who does or doesn't obey the laws of the land?

The choice is ours to make.

— Tamar Jacoby is a senior fellow at the Manhattan Institute and author of Someone Else's House: America's Unfinished Struggle for Integration.

During World War II, the "Home Front" was a metaphor intended to get people to turn in their used tires for recycling and not grumble too much about the rationing of butter.

But in today's war, "Home Front" is no longer a metaphor. The enemy overseas has no chance of prevailing against our superb armed forces, so his only option is to come here and kill our children in their beds.

As long as this is true, blocking the enemy's ability to enter our country must be the central objective of homeland security. Everything else in the war against the Islamic militancy — special-forces strikes, intelligence cooperation, stopping money transfers, even invading Iraq — can only be justified if they support this overriding goal.

Most Americans understand that immigration control is a critical tool for protecting America's national interests. A Zogby International poll taken in the wake of the 9/11 attacks found that the overwhelming majority of Americans, across all races, regions, incomes, and political beliefs, blamed lax border control and screening of immigrants for contributing to the attacks and believed that improved immigration enforcement would reduce the likelihood of future atrocities.

Nor is this mere scapegoating. Terrorists have exploited all aspects of our feckless immigration system to penetrate our society. Our 2002 report on the immigration histories of the (then-) 48 foreign-born, radical Muslim terrorists who committed crimes in the U.S. since 1993, one-quarter were illegal aliens when they committed their crimes and close to half of the total had documented violations of the immigration law at one point or another. Out of that 48, 19 were the 9/11 hijackers and not one of the 15 whose visa applications escaped shredding should have been granted a visa.

Also, amnesties for illegal aliens have facilitated terrorism. Mahmud "The Red" Abouhalima, a leader of the 1993 World Trade Center bombing, was legalized as a seasonal agricultural worker (he was actually a cabbie in New York) as part of the 1986 amnesty, which allowed him to travel abroad, including several trips to Afghanistan, where he received terrorist training.

Furthermore, terrorists have engaged in fraudulent marriages to American citizens, such as Khalid Abu al Dahab, who raised money and helped recruit new members for al Qaeda. Others have provided false information on their applications for green cards, like Sheik Omar Abdel Rahman. And at least eight terrorists held jobs illegally.

No system that allows a Mexican busboy to sneak in can stop an al Qaeda terrorist. And any attempt to limit immigration-law enforcement to people from Muslim countries is bound to fail; not only would it be politically unsustainable, but the terrorists would simply come from other countries. In fact, the FBI warned local law enforcement last year that, because of increased scrutiny of visitors from Muslim nations, al Qaeda is discussing "hijacking a commercial airliner using Muslim extremists of non-Arabic appearance," specifically "Chechen Muslims affiliated with al Qaeda, but already present in the United States."

A greatly stepped-up effort to end the lawlessness that reigns in our immigration system would help protect us from the enemy and, as a bonus for politicians, would be met with overwhelming support by the American people. On the other hand, if another huge attack is carried out by foreign-born terrorists, no one will be able to say he wasn't warned — and there will be hell to pay for this administration.

— Mark Krikorian is executive director of the Center for Immigration Studies.