By Dianne Feinstein

Originally appeared in the San Francisco Chronicle

Zacarias Moussaoui, a French citizen and the suspected 20th hijacker on 9/11, traveled to the United States through the Visa Waiver Program. He was arrested less than a month before the 9/11 attacks.

Richard Reid, the so-called Shoe Bomber, was en route from Paris to Miami when he tried to blow up the plane. A British citizen radicalized in Afghanistan and Iraq, Reid was allowed to travel using the Visa Waiver Program.

The perpetrators of the Charlie Hebdo and more recent Paris attacks were citizens of France and Belgium. Unless they were blocked for another reason, such as being on a terrorist watch list, they could have traveled with little scrutiny to the United States through the Visa Waiver Program.

The Visa Waiver Program must be strengthened to prevent individuals who would harm us from reaching the United States.

Each year, more than 20 million individuals from 38 countries use the Visa Waiver Program. They are able to travel without a traditional visa, which means they don’t have to submit fingerprints or a photograph, and they skip the in-person interview at a U.S. consulate or embassy.

Instead, individuals fill out an online form that requires only basic biographical information. This can be approved within seconds.

We cannot verify a traveler’s true identity by using their face or their fingerprint until the traveler arrives for the first time at a U.S. airport — far too late if his or her goal is to bring down a plane.

With as many as 45 million lost or stolen travel documents on the black market — which can be purchased for as little as $750 — we need to make sure we know exactly who is traveling to the United States.

I recognize the benefits of the Visa Waiver Program, especially in California where tourism is a $117 billion industry.

But I have long had concerns about security gaps in the program. The rapid growth of ISIL and the waves of foreign fighters traveling from Europe to Iraq and Syria to train only make the situation more dire.

We must reform the Visa Waiver Program to address these emerging threats.

An estimated 5,000 European citizens have traveled to Syria and Iraq to fight. Approximately 2,000 of those are from France.

If they return home and haven’t been identified by law enforcement, they can travel to the United States without a visa in a matter of hours.

A bill I introduced with Sen. Jeff Flake, R-Ariz., the Visa Waiver Program Security Enhancement Act, would address these vulnerabilities and increase the security of the program. The White House supports many of the bill’s provisions and the House has passed similar legislation.

First, individuals who traveled to Syria or Iraq in the past five years would be required to go through the traditional visa process to come to the United States. This means they would have to submit fingerprints and a photograph and have an in-person interview with a U.S. consular official.

Second, our bill would require everyone using the Visa Waiver Program to have an e-Passport, which contains information stored on an electronic chip and is more difficult to forge or tamper with.

Third, the bill would strengthen information-sharing agreements between visa waiver countries and the United States. It would require that existing information-sharing agreements be implemented and help ensure that countries in the program screen passengers against Interpol’s lost and stolen passport database before they get on a plane.

And fourth, in cases where a foreign national has never visited the United States, they would be required to submit fingerprints and a photograph to prove their identity at some point prior to boarding the plane.

Under current law, fingerprints and photographs are only collected once their plane lands. This could allow a foreign fighter the opportunity to bring the plane down or hijack the plane. Our bill’s requirement would provide U.S. law enforcement with the time and information necessary to stop such an attacker.

Photographs of the apparent ringleader of the Paris attacks were featured in the ISIL magazineDabiq nine months before the attacks took place. If he had applied for a visa waiver under this new law, we would have his photograph. Through the use of facial recognition technology, the photograph could be used to prevent him from flying.

It is important to note that this requirement only applies to travelers who haven’t already visited the United States. If they have, their fingerprints and photographs are already on file and they don’t need to resubmit.

The Department of Homeland Security would have flexibility to implement this requirement. Options include using a customs preclearance process, expanding the Global Entry Program, or providing biometric data in advance to the State Department. If Apple can enable individuals to access its iPhones with a fingerprint, then surely there must be an efficient and effective way of obtaining a fingerprint and photo from a traveler at some point in the travel process prior to boarding.

The bill also allows the Department of Homeland Security to prioritize biometrics collection for countries that pose higher risks, such as those with more foreign fighters.

These security enhancements would be paid for with an increase in the fee paid by travelers, not through taxpayer dollars.

The Visa Waiver Program is important for our economy, and I believe we can further secure the program without diminishing its value.

Dianne Feinstein represents California in the U.S. Senate.