It also overlapped with the 2016 presidential campaign, meaning that Republicans hoping to present themselves as tougher than President Obama, a president still hoping to unlace American gun culture, and Democratic candidates hoping to score other political points quickly weighed in with political responses.
What's remarkable, though, is that none of those responses would have prevented the tragedy.
In his Oval Office speech Sunday, Obama offered three responses to what happened in San Bernardino. First, he suggested that people on the government's "no-fly" list should not be allowed to buy guns. Second, he argued that it should be harder to buy "assault weapons." And third, he indicated that those who come to the United States without a visa should be given more scrutiny and that the visa program under which one of the shooters entered the country should be "reviewed."
The shooters in San Bernardino, of course, don't appear to have been on the "no-fly" list. Last year, they flew into Chicago, indicating that their ability to fly wasn't restricted. What's more, it appears that neither shooter was being watched by the FBI.
To the third point, Tashfeen Malik didn't enter the country without a visa. She came on a "fiancé visa," which does include a level of background check (that in this case turned up nothing). No red flags were found as part of that process, which reinforces the concern expressed by FBI Director James Comey when speaking to Congress about refugees this year: The lack of a red flag from intelligence databases is often equal to a green light.
The rifles used by Malik and her husband, Syed Farook, were apparently purchased for them by a third person. The .223-caliber semiautomatic weapons are modified versions of AR-15s, which have been used in previous mass shootings. As used, the weapons were illegal in California thanks to modifications made by the shooters. But the rifles themselves were not — nor were they prohibited under the assault weapons ban that was in place from 1994 to 2014. The term "assault weapon" is not a hard-and-fast definition, so it's not clear what Obama would propose here. But even he didn't call for an outright ban. He simply said that it the country should "make it harder" to buy such weapons.
Hillary Clinton has mirrored the president's call to ban weapons sales to those on the "no-fly" list. She has used that position to attack her Republican opponents after a failed Senate vote last week that would have done precisely that. Sen. Bernie Sanders (I-Vt.) demanded broader gun control measures — though again, it's not clear that those would have kept guns out of the hands of Malik and Farook.
Republican candidates have generally offered one of two responses to the shooting: Defeating the Islamic State and curtailing the number of people arriving in the country from areas with Islamic extremism.
Sen. Ted Cruz (Tex.) compared the screening to which Malik was subjected to the screening used for refugees from Syria — though the latter is more stringent, according to the Department of Homeland Security. Again, Malik passed that screening, and it's hard to see where to draw the line between someone who's never done anything to raise the suspicion of authorities and someone who's been deliberately discreet in plotting to lash out at the United States. Malik arrived from Pakistan after living in Saudi Arabia, not countries at the center of the fight against the Islamic State.
Donald Trump, as usual, takes it one step farther. He used the attack as an argument to more closely watch Muslims, which is the sort of vague proposal that it is hard to fact check or rebut. Given that Farook's co-workers apparently saw no signs that he was becoming radicalized, though, it's not clear that the government would have sussed out anything revealing — save stationing FBI agents outside of the houses of every Muslim in the country. That's pretty far down the slippery slope already. Cameras in every house would probably prevent a lot of crime, too.
Jeb Bush has tried to use the attack as a way of talking about foreign policy, which he views as one of his strengths. Bush, like other Republican candidates (and Clinton), has focused how to beat the Islamic State.
Eradicating the Islamic State would reduce the number of people acting in its name, certainly. But it's not clear whether the new model of terrorism demonstrated in San Bernardino is a function of the Islamic State or of the tools it is using. Terror attacks on U.S. soil preceded the rise of the group, of course. What appears to be new is that the Internet allows the spread of the rhetoric powering the Islamic State outside the boundaries of geography. The Boston bombing in 2013 appears to have been influenced by online material from al-Qaeda, suggesting that it is the availability of material and propaganda more than its source which can be the motivator or catalyst for violent acts.
It's hard not to be fatalistic about this. We've become accustomed to shooting incidents and are becoming accustomed to the idea that people in the United States want to do us harm. One reason that no clear, implementable policy solutions have been proposed might be that none yet exist.
Meaning that the San Bernardino debate becomes between left and right instead of between two viable approaches.