They used to say one man's terrorist is another man's freedom fighter. Nobody thinks like that any more. Even the most gung-ho interventionist would be hard-pressed to market freedom fighters from Syria. Nowadays, we see Muslim refugees as potential terrorists. Almost 15 years on, United States society is as fearful of terror strikes as it was after the 9/11 attacks. It is little use brandishing statistics. Fear is a serpent with a mind of its own. Ten months before a US presidential election, terrorism overrides the economy as the voter's main worry. Society's darker instincts are growing.
Last Thursday, a man with a gun tried to shoot a police officer in Philadelphia. The officer survived. The assailant, a US-born African-American, claimed to be acting in the name of the Islamic State in Iraq and Syria (ISIS). Cable news channels went into "ISIS terror" overdrive. None dwelled on any of the 280 actual homicides in Philadelphia last year. Two men, both of Iraqi-Palestinian origin, were arrested in California and Texas on suspicion of having ties to ISIS. Both came to the US as refugees. Meanwhile, a prison corrections officer in California was released on bail after attacking Muslim men praying in a park, yelling "Allah is Satan". It followed a surge of attacks on US mosques and Muslims in the past six weeks.
Each in isolation is a minor event. Taken together - and coupled with ubiquitous media coverage - they prime the public for the next terror assault.
Both sides of the US political divide are also stoking it. President Barack Obama does so inadvertently. Whenever he cites terrorism as a reason to tighten gun control, gun sales surge. Since the attacks in San Bernardino last month, which took 14 lives, US gun sales have shot to an all-time high. Last month, there were 3.3 million background checks on individual gun purchasers, which was almost a fifth higher than the previous monthly record.
Gun manufacturers have enjoyed a golden era under Mr Obama. Americans are buying almost twice as many firearms as when he took office, The New York Times has reported. The share price of Smith & Wesson and Sturm, Ruger, the two largest gun companies, have risen more than 900 per cent apiece since he took office, against 147 per cent for the Standard & Poor's index as a whole. Many Americans are buying firearms because they fear the window is closing. They are almost certainly mistaken. Mr Obama's modest proposals will make little difference, even if they survive a hostile Congress.
Many, though, are also thinking of their own security. Public support for tighter gun control has actually fallen since the San Bernardino and Paris terror attacks, in spite of the fact that the terrorist couple in California found it so easy to acquire an arsenal of weapons. Mr Obama does himself few favours by refusing to use the term "radical Islamist terrorism". He sticks to "violent extremism", which fuels the perception - not just on the right - that his administration is imprisoned by political correctness.
Republicans, by contrast, are consciously amplifying public fear. Though America will take only 10,000 Syrian refugees this year, more than half of US states have said they will refuse to host any. Mr Donald Trump, the Republican front runner, has called for a pause on all Muslim immigration "until we can figure out what is happening".
Senator Ted Cruz, who looks likely to win the first presidential caucus in Iowa next month, has hired an analytics firm to trawl social media for voters with signs of "neuroticism". Like most of his rivals, Mr Cruz misses no chance to hype up the terror threat. "We need a retroactive assessment of all refugees from high-risk countries who have been admitted," said Mr Cruz after the Iraq-born refugees were arrested for suspected ISIS links. Little wonder public opinion has been shifting. Only 38 per cent of Americans think the US should accept any Muslim Syrian refugees (56 per cent would accept Syrian Christians). More Americans support sending US ground troops to fight ISIS than oppose it.
Conventional wisdom tells us that neither Mr Trump nor Mr Cruz is likely to be the nominee. It also says that if either pulled it off, they would stand no chance of defeating Mrs Hillary Clinton. But seasoned observers have been wrong about the Republican race since it began. Here is another scenario. One or the other firebrand takes the nomination. They struggle to match Mrs Clinton in the polls. Then the election is upended by a Paris-style terror attack. If you think this is far-fetched, consider the couple in San Bernardino. They had enough firepower to pull off a far larger slaughter.
The left worries that intelligence agencies are sucking up too much data, jeopardising freedom. They ought to be equally worried about the lack of capacity and legal authority to sift the data and join the dots. The right worries that US Muslims are a fifth column. By goading such fears, they make law-abiding citizens feel unwelcome and fuel the alienation that breeds terrorists. This is what ISIS wants. At any time, public fearfulness is troubling. In an election year, we should be especially wary.
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