There is no silver bullet to protect Americans from every would-be terrorist. The case of Tashfeen Malik is a unsettling example of how even someone who arrives in the U.S. as the spouse of an American may in fact be a twisted fanatic willing to abandon her baby in order to shed innocent life.
According to the Los Angeles Times, Malik entered the U.S. on a fiancee visa. "After a background check by the FBI and the Department of Homeland Security," the Times explained, "she was granted a conditional green card last summer."
The so-called K1 visa that Malik used is one of many kinds of visas, and the background checks are supposed to flag any ties to terrorists. But of course maybe Malik hadn't established any such links at the time — which was well before she reportedly pledged allegiance to an Islamic State leader.
Yet if a terrorist wants to enter the U.S., finding a suitable marriage partner seems like one of the least likely options. A far more appealing course would be to enter under the Visa Waiver Program, which lets in more than 20 million people from 38 countries each year without a visa.
In 2013, for example, more than 2 million of the visitors were from France and Belgium, which have seen a stream of homegrown radicals travel to the Middle East to fight for the Islamic State.
It's not as if visitors under the waiver program are unscreened. They are checked against relevant databases at several points to see if they are security threats. And the waiver program itself requires participating countries to share intelligence about terrorist suspects as well as criminal and biometric data, in addition to data about lost and stolen passports.
But concern that would-be terrorists could nevertheless exploit the Visa Waiver Program has been growing — and spiked after the massacres in Paris.
That's why both houses of Congress are looking at tightening the program.
Both House and Senate versions require greater compliance by partner countries in information and intelligence sharing. And they require anyone who has traveled to Syria or Iraq in the past five years to get a traditional visa rather than be eligible for a waiver.
A regular visa requires the traveler to interview with a consular official and to supply more information than the waiver process demands, then wait for a period.
It would be foolish and counterproductive to junk the waiver program altogether, since the vast majority of those who use it come to the U.S. for legitimate reasons. But the events in San Bernardino are a reminder that even valuable programs that govern entry into the nation need a close look every now and then.