Following the Charlie Hebdo massacre in Paris this month, White House spokesman Josh Earnest briefly became an Islamic theologian. At issue was why President Obama’s administration, unlike the leadership of France, wouldn’t describe the killers as adherents to “radical Islam.”

Pressed by NPR’s Mara Liasson, Earnest explained to reporters that the terrorists tried to “invoke their own deviant, distorted view of Islam in order to justify” the attacks.

It’s easy to see the absurdity in saying that men who shout “Allahu Akhbar” before they kill Jews, cartoonists and French police officers are not radical Muslims. But Earnest was not freelancing, he was articulating a long-standing U.S. policy, not only for Obama but also his predecessor, George W. Bush. Both administrations have said repeatedly since Sept. 11, 2001, that radical Islam is not Islamic.

There is a reason for this: The long war against radical Islamic terrorists requires at least the tacit support of many radical Muslims.

It sounds strange. But as Emile Nakhleh, who was one of the CIA’s top experts on political Islam between 1993 and 2006, told me, there was a recognition following the 9/11 attacks inside the Bush administration that many supporters of the Wahhabi strain of Islam favored by Al-Qaida and its allies were not plotting attacks on the West. In some cases, such as the Kingdom of Saudi Arabia, the purveyors of Wahhabism were long-standing American allies. “There was the 2-ton elephant in the room, and that is Saudi Arabia,” Nakhleh said.

So Bush for the most part opted instead to talk about the enemy as “evildoers” or “extremists,” even though on some occasions he went off message. It’s why Bush’s second secretary of state, Condoleezza Rice, condemned as “offensive” the Danish cartoons of Mohammed in 2006 after they sparked riots across the Muslim world.

Obama took this approach even further. In 2009, he delivered two important speeches addressed to the Islamic world, quoting Koranic verse, and sent an envoy to the Organization of the Islamic Conference. Bush didn’t want a quarrel with Islam and, in his first term, Obama wanted Islam to be a strategic partner against Al-Qaida.

In 2010, top counterterrorism adviser John Brennan said the administration would not describe the enemy as “jihadists” because “jihad is a holy struggle, a legitimate tenet of Islam, meaning to purify oneself or one’s community, and there is nothing holy or legitimate or Islamic about murdering innocent men, women and children.”

Last fall, Obama said that the Islamic State in Iraq and the Levant (ISIL) — which has imposed extreme sharia law on much of Syria and Iraq — was neither a state nor Islamic.

Now, it’s important to note that Obama made those remarks when he was announcing a new air war against ISIL. It’s reminiscent of how Bush said Islam was a “religion of peace” just as his administration was preparing to drive Al-Qaida and the Taliban out of Afghanistan.

This is not an accident. Elliott Abrams, who served in senior National Security Council positions throughout the Bush administration, told me: “We were invading two Muslim countries and we were being accused of being at war with Islam. So the administration wanted to make it very clear that we are not at war with Islam and every Muslim in the world.”

All of this gets to a paradox of the war on terror. It has never been a war on the tactic of terrorism, and it has always been a war against networks of radical Islamists. But to wage that war, the United States has had to ally with Muslim countries and people, many of whom believe the state should punish apostates, adulterers and blasphemers.

Sadly, large pluralities of Muslims in countries allied with the Unite States in the war on terror disavow the tactics of terrorism but endorse the aims of radical Islam. For example, 74 percent of Muslims in Egypt feel that sharia should be the “country’s official legal code,” and an equal majority say it should apply to non-Muslims as well as Muslims, according to a 2013 Pew survey. Three-quarters of Pakistani Muslims support laws banning blasphemy. A majority of Muslim Iraqis said they supported “honor killings” of women who engage in premarital sex or adultery.

Given these popular attitudes, even the governments in the Muslim world most actively aiding in the fight against Al-Qaida and the Islamic State have to tread a fine line over fundamentalist religion, and Washington doesn’t want to make that task harder.

It’s possible to imagine a world where American presidents would speak plainly about radical Islam. It likely would be a world in which the United States stopped waging a global war on terror.

So for the time being, don’t expect the United States to publicly speak of a war against radical Islam, even as it continues to kill radical Muslims throughout the Islamic world.