GOVERNOR Chris Christie of New Jersey earned a striking round of applause at a forum for Republican presidential candidates on the afternoon of December 3rd. It came as the governor scolded Barack Obama for being slow to confirm that a mass shooting the day before in San Bernardino, California, was a work of terrorism. From the moment he had begun to watch the news unfold, Mr Christie said, he had been “convinced” that this was a terrorist attack. His audience—hundreds of members of the Republican Jewish Coalition (RJC), a conservative group—clapped loudly and with a distinct air of vindication. From his perch in the press gallery, your correspondent pondered that applause. Objectively, it is terrible news that the mass shooting in California, which left 14 dead and wounded 21, appears, indeed, to have been inspired by the death cult that is the Islamic State. On December 4th, the FBI said that the massacre was being investigated as an act of terrorism. Ever since the slaughter in Paris last month, Americans have been justifiably anxious that a terror attack would occur here. Now it seems to have happened.

At the moment that Mr Christie spoke details were still emerging by the hour, but even then something still more frightening was known: that the alleged perpetrators were an American-born Muslim, Syed Rizwan Farook, and his Pakistani-born wife, Tashfeen Malik. That Farook was an American citizen is really bad news. If it is difficult to track the movements of foreign nationals in and out of America, it is far harder to track native-born citizens, who need no visas or visa waiver forms to come and go.

It is depressing news, moreover, that Farook appeared to be well-assimilated in America, the land of his birth—and yet still turned to the path of extremist violence. In Europe, politicians alarmed by reports of radicalisation among Muslim populations often point to high unemployment, poverty and other social ills as drivers of alienation. If only young Muslims can be offered more opportunities, they say, then perhaps Islamic extremism will have less appeal. Yet in this case in California, early reports all talked of Farook’s well-paid job as a health inspector with his local county government. It later emerged that his brother had served honourably in the American navy. Outwardly, in short, Farook was a success story. That someone of his background still fell under the dark spell of fanaticism is really dismaying.

Finally, it is sobering news that the two killers had access to near-military levels of weaponry. It is almost impossible to pass federal laws to restrict access to the most powerful semi-automatic weapons. California, a left-of-centre state, has some of the strictest gun laws in America. Yet that did not stop the murderers from acquiring, apparently legally, variants of the AR-15 semi-automatic rifle, two pistols and thousands of rounds of ammunition. What that shows, unhappily, is that even the toughest gun laws in America are not much use when it comes to the only form of gun control that might actually stop or limit some massacres: blocking access to murderously powerful guns.

All in all, the California shooting is a nightmare, its every detail pointing to the extreme difficulty of preventing domestic acts of terror inspired by the blood-soaked fanaticism of the Islamic State. That being so, what explains the applause from the conservative audience in Washington?

Put simply, America is so bitterly polarised that as soon as a mass shooting occurs, the political classes hold their collective breath. For everyone understands that a zero-sum game is underway: to learn whether this was an ideological act of slaughter, ripe for political exploitation.

Republicans had been on the defensive since a mass shooting carried out at a clinic that conducts abortions in Colorado on November 27th by a violent and unstable white man whose many hatreds apparently included abortion and Mr Obama. Bluntly, for many Democrats, that was a killing that vindicated all their suspicions about the violence that lurks on the fringes of conservative politics. In contrast, once news broke that the killers in Californian were Muslims, conservative commentators and Republican members of Congress seized the chance to denounce Mr Obama and his administration for failing to grasp the threat posed by Islamic extremism.

Another presidential candidate, Senator Ted Cruz of Texas, told the RJC Forum: “Whether or not the current administration realises it or is willing to acknowledge it, our enemies are at war with us and I believe this nation needs a wartime president to defend it.” Jeb Bush, the former governor of Florida, was one of several candidates at the forum to chide Mr Obama and Hillary Clinton, the frontrunner for the Democratic Party’s presidential nomination, for failing to use the right language. Mr Bush complained: “The brutal savagery of Islamic terrorism exists, and this president and his former secretary of state cannot call it for what it is.”

Not for the first time, Donald Trump, the Republican front-runner, took a familiar conservative talking-point and added a shrill descant of conspiracy. Mr Obama will not say the words radical Islamic terrorism, the businessman told RJC members. “He refuses to say it. There’s something going on with him that we don’t know about.”

Democrats have attempted to push back by casting Republicans as extremists who will not pass modest gun safety measures. Party leaders on Thursday tried to force votes in the Senate on a long-stalled measure that would increase the number of gun sales subjected to background checks for criminal records and histories of serious mental illness, and on a second measure that would prevent people on a federal terrorist watch-list from buying guns.

That prompted a legalistic objection from the new Republican Speaker of the House of Representatives, Paul Ryan. Yes, he told MSNBC, a cable news channel, people were calling for those on the federal “no-fly” list for suspected terrorists to be barred from buying guns. But people are “arbitrarily placed” on watch-lists by government officials, some of them by mistake, he said. To deny them the right to buy a gun would “deprive them of their constitutionally protected due-process rights.”

Mr Cruz—a man of considerable eloquence and even greater ambition who hopes to inherit Mr Trump’s voters should the billionaire fade in the polls—cranked the anti-government rhetoric up to a still-higher notch. Rather than name radical Islam and defeat it by “killing the terrorists”, Mr Obama and Mrs Clinton are “obsessed with disarming the American citizenry,” the senator told Breitbart News, a website. Seeming to conjure up an image of private citizens at war on America’s streets, Mr Cruz went on: “You don’t get rid of the bad guys by getting rid of our guns. You get rid of the bad guys by using our guns.”

Mr Cruz marked Friday afternoon by hosting a long-planned gun-rights rally at a shooting range in Iowa, which will in February hold the first selection contest of the 2016 presidential primary season. To the senator from Texas, the lesson from California is that “to the surprise of no one”, strict gun laws “failed to prevent this horrific attack.” That is true. Logic would suggest giving still stricter gun laws a go, along the lines of those imposed in Britain or Australia after mass shootings. Politics makes that an empty hope.

What of the Republican demands to name extremist Islam as the enemy with which America is at war? Some, notably Mr Cruz and Mr Trump, go further. They have proposed singling out Muslims for formal discrimination. Mr Cruz wants a law barring Muslim refugees from Syria, though he would admit Christians from that country. Mr Trump has suggested that Muslims need special surveillance.

But here is a question to ask Messrs Christie, Cruz, Bush, Trump et al. What do they imagine would happen the moment after a president spoke the words that they so long to hear, declaring America at war with radical Islam? After conservatives had savoured that moment of bracing candour, what then?

There are an estimated three million Muslim-Americans in the country. How do the 2016 presidential candidates propose to defeat Islamic terrorism without the help of those Muslims, who are better placed than anyone to report radicalisation at their local mosque, in their community or in their own family? Looking overseas, how do those presidential hopefuls plan to defeat the fanatics of the Islamic State without Muslim allies?

Keeping Americans safe from terrorism is a hard task that is only growing harder. The implications of this week’s mass shooting in California are horrible. And yet both parties reacted by trying to extract political advantage from those events. Hold the applause.