The Bush administration didn’t get serious about cracking down on illegal immigration and illegal workers until the last two years. The laxness of those early years proved that when the feds mostly shrug at border breaches and undocumented workers, it only gives aliens a larger incentive to enter the country.

After all, once they’re across the border, there’s virtually no chance they’ll be caught and deported. In fact, roughly a third of the illegal immigrants in the U.S. are people who came here with temporary visas but never left. Interior law enforce­ment is the only way to remove them.

Instead of backing away from the tentative Bush approach, DHS ought to increase workplace enforcement. Federal officials need to work more with state and local govern­ments to put in place mechanisms such as “E-verify,” a system that can ensure employers aren’t hiring illegal immigrants and can crack down on those already living here illegally.

Finally, the federal government can slow the tide by helping countries in Latin America develop healthier economies. That way, our southern neighbors wouldn’t feel compelled to leave home. As for Mexico specifically, the U.S. needs to help its government battle the drug cartels that are trying to destabilize it. The drug war on our southern border is a true war, one that Mexico cannot afford to lose.

Enforcement makes a real difference. The number of illegal aliens in the U.S. is dropping, partly because of the economy, but also because of enforcement. Now is not the time to back off.

The threats to Homeland Security have changed over the years. America’s approach to protecting itself must change as well. Securing the border and upholding the rule of law are a big part of that.