Flying internationally imposes enough petty hassles on harried travelers already, but the new U.S. requirement that European visitors register 48 hours before flying to the United States is a small price to pay for visa-free travel across the Atlantic.

The visa provision is embedded in a new law passed by Congress and signed by President George W. Bush earlier this month implementing major recommendations of the special 9/11 Commission. Beginning in 2008, Europeans visiting the United States will need to provide such basic information as name, passport number and travel plans within the United States 48 to 72 hours before their departure.

Complaints from our European friends have been loud and talk of tit-for-tat retaliation hangs in the air with the European Commission threatening a similar scheme for Americans visiting Europe.

Calmer heads should understand that the new law represents a reasonable effort to thwart terrorists without unduly discouraging or burdening tourists and business travelers. The visa waiver program remains firmly in place. About 15 million Europeans visit the United States each year through the program, which allows them to stay in the United States for up to 90 days without obtaining a visa.

This is a privilege not available to 85 percent of the world’s population.

The visa waiver program stimulates tourism and business dealings across the Atlantic. A U.S. Commerce Department study estimates that the program encourages an extra 3 million visits a year, pumping $28 billion extra into the U.S. economy. More trans-Atlantic travel also fosters greater understanding and cooperation on a broad range of issues from the environment to national security.

The advance notice provision preserves the visa waiver program while allowing U.S. security officials to compare the identification of travelers to terrorist and criminal “watch lists” before they board a plane bound for the United States.

The requirement gives security officials extra time to vet the passenger manifests. It also avoids the awkward necessity of detaining and returning people after they have actually arrived on the ground. And it should stop the delaying of U.S.-bound flights while on the ground at European airports because of last-minute checks of passenger manifests.

The new requirement is more a change in timing than a demand for new information. Travelers must already fill out an arrival card while in the air containing the same basic information required by the new law, and travelers already provide much of the same information when buying their tickets. The travel industry itself has a strong incentive to help their customers adopt their travel planning to the new law.

Australia’s almost identical Electronic Travel Authorization program proves such a scheme can work smoothly and without discouraging legitimate travel.

The advance notification remains far simpler and less intrusive than applying for a visa. Travelers from non-visa-waver countries must still pay a $100 fee, provide far more information, and physically travel to a U.S. embassy or consulate for an in-person interview. They also face the real prospect that their visa application will ultimately be rejected on non-security grounds. Residents of visa-waver countries should count their blessings.

Advance notification serves as a prudent inoculation against far more onerous restrictions. One House amendment to the 9/11 commission’s recommendations offered in June would have eliminated financing for the visa waver program entirely.

While the amendment failed 76–347, another terrorist incident on U.S. soil could easily revive the effort and put the visa-waiver program in jeopardy. Advanced notification makes another attack less likely.

Neither Americans nor our European friends should be naïve about the possibility that the threat could come via Western Europe. Great Britain and other EU members are combating their own homegrown terrorist cells. Another Richard Reid or Mohammed Atta cannot be lightly dismissed — both traveled to the United States from Europe. The advanced notification system, combined with the ongoing intelligence cooperation between EU governments and the United States, offers the best hope of keeping the visa waiver program going.

Every country has a sovereign right to know who is crossing its borders and to exclude people who pose a real threat to its citizens. In an ideal world, Americans and Europeans would move as freely across the Atlantic as they do across the English Channel, but that world has not yet arrived yet, and thanks to radical Muslim terrorists, it will not arrive for some time.