After the terrorist attacks on Sept. 11, 2001, Americans became rightly concerned about two serious issues -- thwarting the international travel of terrorists and getting serious about enforcing U.S. immigration laws. Most of what was done immediately after 9/11 amounted to simply making it more difficult to travel to the United States from overseas.

Such caution was certainly understandable, but this approach isn't sustainable over the long term. International trade and travel benefit the United States enormously, accounting for more a third of GDP. America requires safeguards that will keep us safe, free and prosperous.

Congress seems to realize that a lot more can be done to make international travel both more secure and more free, and lawmakers have picked a good place to start doing both -- with the Visa Waiver Program (VWP).

Under VWP, the U.S. and 27 countries have agreements that permit citizens to travel among them for 90 days using their passports without getting a visa. The VWP is a boom to tourism and business, bringing into the U.S. an estimated $75 billion to $100 billion a year. It also saves the U.S. government a lot of money and adds security, because it allows the State Department, which issues visas, to shift scarce resources to countries of concern.

VWP hasn't been expanded since 9/11 out of concern that terrorists, criminals or immigration violators might exploit the opportunity to travel here and remain unlawfully. But restricting casual travel with many countries that want stronger ties to America hampers our economy and diminishes our image abroad. Many countries want in VWP. With that in mind, some senators have proposed enhancing security provisions in the program, as well as opening the potential for more of America's friends and allies to participate in VWP. It's a win-win proposal.

There are many reasons why it's time to start thinking about strengthening and expanding VWP. Friendly and allied countries worldwide are doing much more to thwart terrorist travel than they did before 9/11.

Every traveler that comes to the U.S., even those in VWP, undergo terrorist and criminal screening. International air traveler bound for the United States are checked against an integrated terrorist watch-list. In addition, before they even depart for the U.S., travelers have already been screened through the Advance Passenger Information System (APIS). With APIS, all international inbound flights send a passenger manifest before hand. Since October 2002, air and sea carriers under the VWP submit both APIS arrival and departure manifests electronically to the Department of Homeland Security for screening and analysis. According to the department, APIS already has been used to uncover drug- and human-smuggling operations.

All countries hoping to participate in VWP have also agreed to implement an e-passport to prevent passport tampering and fraud. The e-passport includes fingerprints and a digital picture. In addition, VWP requires travelers from participating countries to carry a machine-readable passport, which makes it easier to record and analyze travel data.

In addition, Homeland Security Secretary Michael Chertoff has proposed a number of enhancements for VWP which would be mandatory for all countries already in the program. These include more routine sharing on passenger information, timely and accurate reporting on lost and stolen passports, and stronger agreements on repatriating illegal aliens, as well as cooperation in the Federal Air Marshal program.

The Senate bill adds other security guarantees as well, including establishing a mandatory exit check to ensure visitors have left the country. According to a study by the General Accountability Office, most individuals who overstay and illegally remain in the United States do not come from VWP countries. It's important to ensure that countries that want to enter the program don't abuse the system. The best way to do that is to ensure that travelers do not overstay. Requiring VWP travelers to use mandatory exit checks will provide rock-solid evidence whether or not the rules are being followed. Countries that do not measure up can be immediately dropped from the program.

Expanding VWP would make America more secure and would strengthen the enforcement of U.S. immigration laws. VWP "raises the bar" for safe and secure international travel and countries that are willing to participate will be committing to enforce higher standards, more vigilant security, and stepped-up enforcement.

We can't win the War on Terror by trying to seal America off from the rest of the world. Winning must include safe and open international travel for Americans and their friends and allies. VWP reform is the next step in the right direction.

Helle Dale is director of the Allison Center for Foreign Policy Studies at The Heritage Foundation (heritage.org), where James Jay Carafano, Ph.D., is a senior research fellow.