In the fall of 1990—around the time U.S. troops arrived in Saudi Arabia, enraging Osama bin Laden—the historian Bernard Lewis sounded an alarm in The Atlantic about brewing anti-Americanism in the Muslim world. “[W]e are facing a mood and a movement far transcending the level of issues and policies and the governments that pursue them,” he wrote. “This is no less than a clash of civilizations—the perhaps irrational but surely historic reaction of an ancient rival against our Judeo-Christian heritage, our secular present, and the worldwide expansion of both. It is crucially important that we on our side should not be provoked into an equally historic but also equally irrational reaction against that rival.”

America’s two post-9/11 presidents, George W. Bush and Barack Obama, attempted a balancing act: combatting jihadist terrorism while seeking to avoid the impression that the Western and Muslim worlds were engaged in the kind of clash Lewis described.

Donald Trump may soon steer the government in a different direction. Several of the president-elect’s national-security appointees have argued that the United States is at war with “radical Islamic terrorism,” or “radical Islam,” or something broader still, such as “Islamism.” They have described this war as a primarily ideological struggle to preserve Western civilization, like the wars against Nazism and communism. The war is not confined to extremist Sunni Muslims or extremist Shia Muslims; the Islamic State and the Islamic Republic of Iran are seen as two sides of the same coin. Notably, these appointees have put forth this sweeping vision before taking charge of the nation’s security—before a terrorist attack has occurred on their watch.

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Bush certainly described his War on Terror in ways that evoked a civilizational clash, pitting freedom-lovers against the totalitarian successors of the Nazis and communists. But he emphasized that Islam was not one of the clashing sides—that the terrorists had perverted the “peaceful teachings of Islam.” “Some call this evil Islamic radicalism,” he said in 2005. “Others militant jihadism. Still others Islamo-fascism. Whatever it’s called, this ideology is very different from the religion of Islam.”

Barack Obama has downgraded Bush’s War to a fight, and the enemy from Terror to specific terrorist groups. He rejects the notion of a clash of civilizations, both because he thinks it overestimates the threat of terrorism to the United States and because he doesn’t want to affirm the jihadists’ narrative of a struggle between Islam and infidels in the West. When a U.S. president uses “loose language that appears to pose a civilizational conflict between the West and Islam, or the modern world and Islam, then we make it harder, not easier, for our friends and allies and ordinary people to resist and push back against the worst impulses inside the Muslim world,” Obama told The Atlantic’s Jeffrey Goldberg.

Obama’s approach has produced a backlash that may shape policy in a Trump administration. For years now, Republicans have condemned Obama’s avoidance of the term “radical Islam,” arguing that it represents the president’s failure to properly assess and address the threat. Radical Islam, Obama’s critics contend, is what it sounds like: radicalism rooted in the religion of Islam. Where Obama sees “violent extremism,” his critics see militant religiosity. Where Obama sees a clash within Islamic civilization—between a tiny faction of fanatics and the vast majority of Muslims—his critics see a clash between Western civilization and a small yet significant segment of the Muslim world. Where Obama sees a weak enemy that is getting weaker, his critics see a strong enemy that is getting stronger. Where Obama sees limits to what the U.S. can do on its own to eradicate radical interpretations of Islam, his critics see an appalling lack of effort by the U.S. government. Where Obama sees a serious but manageable national-security threat, his critics see an ideological and civilizational challenge to the free world.

Trump has gone further than many other Republican leaders in advancing the counterargument to Obama—not just in his proposed policies, like banning or severely restricting Muslim immigration to the United States, but also in his rhetoric. “I think Islam hates us,” Trump said earlier this year. Asked if he was referring to “radical Islam,” he responded, “It’s radical, but it’s very hard to define. It’s very hard to separate. Because you don’t know who’s who.”

Several members of Trump’s emerging team have described the threat in similarly stark and broad ways. “We’re in a world war against a messianic mass movement of evil people, most of them inspired by a totalitarian ideology: Radical Islam. But we are not permitted to speak or write those two words, which is potentially fatal to our culture,” writes Michael Flynn, Trump’s pick for national-security adviser, in a book he published this summer with the conservative writer Michael Ledeen.

“I don’t believe all cultures are morally equivalent, and I think the West, and especially America, is far more civilized, far more ethical and moral, than the system our main enemies want to impose on us,” Flynn adds.

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“Not all the world’s 1.6 billion Muslims are extremists or terrorists. Not by a long shot,” wrote Flynn’s incoming deputy, K.T. McFarland, in March. “But even if just 10 percent of 1 percent are radicalized, that’s a staggering 1.6 million people bent on destroying Western civilization and the values we hold dear. The fascists wanted to control the world. So did the communists. But the Islamists want to brutally kill a significant percentage of the world—and that is anyone standing in the way of their end-times caliphate.” Jeff Sessions, Trump’s choice for attorney general, has invoked America’s “containment” strategy during the Cold War, noting that there “can be no compromise with this form of radical Islam.”

As the head of Breitbart News, Steve Bannon hosted a radio show featuring numerous guests who claimed that radical Muslim ideologues were clandestinely infiltrating the U.S. government and trying to extend their belief system across the country. (Flynn has similarly warned, without compelling evidence, that Islamic Sharia law is encroaching on the U.S. legal system.) In a 2014 speech to the Human Dignity Institute in the Vatican, Bannon, who will be Trump’s chief strategist in the White House, characterized the current war against “jihadist Islamic fascism” as the latest stage of an existential, centuries-old struggle between the Judeo-Christian West and the Islamic world:

If you look back at the long history of the Judeo-Christian West struggle against Islam, I believe that our forefathers kept their stance, and I think they did the right thing. I think they kept it out of the world, whether it was at Vienna [presumably during the Battle of Vienna in 1683], or Tours [presumably during the Battle of Tours in 732], or other places. … We’re in a war of immense proportions. It’s very easy to play to our baser instincts, and we can’t do that. But our forefathers didn’t do it either. And they were able to stave this off, and they were able to defeat it, and they were able to bequeath to us a church and a civilization that really is the flower of mankind…

Mike Pompeo, the Kansas congressman who Trump has tapped as his CIA director, has described the clash in more nuanced terms, stressing that Islam should not be equated with extremism. But he nevertheless claims that Obama has grossly underestimated the danger of jihadism. “This administration will go down in history as having, for the first time, put America in a place, from a national-security perspective, that it has not found itself [in] in anyone’s lifetime in this room,” he said in a 2015 speech to an audience in Wichita that included many people who clearly were alive during the nuclear brinksmanship of the Cold War. “The line is drawn not between faith but between extremists, and those who accept modernity and those who are barbarians. We should understand that line, and we should never be fearful to walk right up to the line, find those on the other side, and crush them.”

Obama’s policies are misguided because he misunderstands the essence of the jihadist threat, Trump’s advisers argue. This is why Flynn, for example, has placed such importance on the words “radical Islam.” They are meant to indicate that many leaders of groups like ISIS and al-Qaeda are genuine ideologues, adherents to the fundamentalist Salafi strain of Islam. If these leaders are thought of merely as violent nihilists to be bombed, those who are taken out will inevitably be replaced by other true believers, and the war will never end.

Flynn arrived at these conclusions after interrogating terrorist suspects in Iraq and Afghanistan as an intelligence officer in Joint Special Operations Command. As he told James Kitfield in October:

Over the course of all those interrogations, I concluded that “core Al Qaeda” wasn’t actually comprised of human beings, but rather it was an ideology with a particular version of Islam at its center. More than a religion, this ideology encompasses a political belief system, because its adherents want to rule things—whether it’s a village, a city, a region or an entire “caliphate.” And to achieve that goal, they are willing to use extreme violence. The religious nature of that threat makes it very hard for Americans to come to grips with.

Framing the fight as an ideological struggle, however, tends to blur the distinction between radical Islam, the political movement known as Islamism, and the religion of Islam. Consider this bewildering exchange between Flynn and the journalist Mehdi Hasan in January:

Flynn: We are at war with a radical component of Islam. … Islam is a political ideology based on a religion.

Hasan: Islam is?

Flynn: That’s what I believe and that’s how I like to—

Hasan: Sorry, do you mean Islamism? Or Islam? Sorry, I’m confused here.

Flynn: Islamism. Islamism, probably better—

Hasan: OK, you’re not saying the religion of Islam is a political ideology?

Flynn: A political ideology based on a religion.

The ideological frame also invites a response that goes well beyond military tactics like drone warfare and air strikes, which Flynn argues Obama has relied on too heavily. Flynn has called for Cold War-like information campaigns that promote Western values and expose “the failures” of radical Islam. Pompeo, an evangelical Christian, has argued that more Muslim leaders need to speak out against terrorism in the name of Islam, noting that Protestant leaders have condemned the hateful actions of the Westboro Baptist Church in his state. “There is a battle of interpretation within Islam,” he’s said. “It’s not enough to deny responsibility, saying one’s own interpretation doesn’t support terrorism. Moderate imams must strive to ensure that no Muslim finds solace for terrorism in the Koran.”

Flynn has also urged the U.S. government to help Middle Eastern countries overhaul their economies and develop energy sources other than oil, in an effort to undermine the socioeconomic grievances that in his view make jihadist groups appealing to young people. When the journalist Fareed Zakaria pointed out that this would require a huge U.S. investment of time and resources that might be disproportionate to the actual threat, Flynn disagreed. “There was a cost, post-World War II, called the Marshall Plan for Europe,” he said. “And Europe is doing pretty darn good.”

Treating radical Islam as a monolithic ideology tends to swell the ranks of enemy fighters as well. During an appearance on The Steve Malzberg Show, for instance, Pompeo offered an expansive definition of the threat facing the United States in Syria: “We got to do it all. [Syrian President Bashar] Assad is a tool of Iran and so to the extent we’re not prepared to push back on Iran in the form of Assad we’re making mistakes. We ought to do that, but it’s not just ISIS either: al-Nusra Front, al-Qaeda. These are all the same two sides of the terror coin and we got to go crush them all.”

“I concluded that ‘core al-Qaeda’ wasn’t actually comprised of human beings. Rather, it was an ideology.”

Many of Trump’s appointees have staked out hardline positions against Iran, which the U.S. government has labeled the world’s top state supporter of terrorism, and heavily criticized the agreement brokered by the Obama administration to restrict the Iranian nuclear program. Pompeo has suggested that Iran’s brand of Shia radicalism is currently a greater challenge to the United States than ISIS’s brand of Sunni radicalism. “At the root of most of the things you see today [in the Middle East] is Iran,” he has said.

When radical Islam is interpreted as a fundamentally anti-American ideology, the ranks of the enemy can also grow to include other anti-American entities. “We’re in a global war, facing an enemy alliance that runs from Pyongyang, North Korea, to Havana, Cuba, and Caracas, Venezuela,” Flynn wrote this summer, in an echo of George W. Bush’s “axis of evil” formulation. “Along the way, the alliance picks up radical Muslim countries and organizations such as Iran, al Qaeda, the Taliban and Islamic State. … If our leaders were interested in winning, they would have to design a strategy to destroy this global enemy. But they don’t see the global war. Instead, they timidly nibble around the edges of the battlefields from Africa to the Middle East, and act as if each fight, whether in Syria, Iraq, Nigeria, Libya or Afghanistan, can be peacefully resolved by diplomatic effort.” (When Bloomberg’s Eli Lake asked how ISIS, North Korea, Cuba, and Venezuela could all possibly be in alliance, Flynn responded, “It was a simpler way to explain the relationships.”)

Traditional U.S. alliances are liable to be reshuffled as well. Trump wants to partner with Russia to fight ISIS, and both Flynn and Pompeo have praised Egypt’s authoritarian leader, Abdel Fattah el-Sisi, for urging a “religious revolution” to purge Islam of its radical elements. “I’ve met President Sisi,” Pompeo said during his 2015 speech. “I’ll say it this way: You don’t find many Thomas Jeffersons over there. Once you accept that … the line needs to be drawn [between] those who are on the side of extremism and those who are fighting against it, of whatever faith we may find them.” Flynn and Pompeo want the U.S. government to amplify Muslim voices like Sisi’s, but their rhetoric on radical Islam also has the potential to alienate Muslim allies.

The ideological war could spur the Trump administration to increase the government’s surveillance powers. “My judgment is that we need to go well past what is violent extremism,” Pompeo said in Wichita. “If you are communicating with, talking to, facilitating, providing resources and money for, educating, training, helping, assisting, and you are part of [a jihadist] network, you are someone who America has every right and indeed an obligation to pull from the streets. We have deep constitutional commitments to what we allow people to do. You all want to be able to talk about your faith. I talk about mine all the time. I want everyone to be able to do that. But when you begin to engage with networks around the world that are part of jihadist organizations, you are no longer talking about your faith but putting people in my neighborhood at risk.”

It could also lead to more intensive vetting of immigrants from Muslim countries. “Questions can be asked: Do you believe in religious freedom, do you believe in Sharia law or the Constitution, and do you respect minorities such as women and gays?” Sessions told The American Thinker in June. “We are not required to admit people if their philosophies or principles are contrary to the Constitution. We have to understand that most Muslims do not adhere to this extreme ideology, but there is nothing wrong to refuse admittance to those who distance themselves from our values.”

Relative to the neoconservatives in George W. Bush’s administration, Trump and his advisers are less inclined to grand visions of nation-building and democracy-promotion overseas. But they endorse Bush-like shows of military force. Jihadist groups “must be denied safe havens, and countries that shelter them have to be issued a brutal choice: either eliminate the Radical Islamists or you risk direct attack yourselves,” Flynn writes.

“[T]he religious and political transformation of Europe that we call the Reformation entailed hundreds of years of very bloody fighting,” he adds. “The world badly needs an Islamic Reformation, and we should not be surprised if violence is involved.”

“The line is very clear,” Pompeo noted in Wichita, channeling Bush. “Are you with us or against us? If you’re with us: God bless you, Godspeed, let’s go get ’em. And if you’re against us: Godspeed, I have a missile that is looking for you.”

As Flynn, Pompeo, and the others tell it, Obama’s refusal to acknowledge radical Islam has kept him from implementing the policies they’re suggesting. But the great irony is that Obama has implemented many of those policies. Obama has launched information campaigns to discredit ISIS and enlisted Middle Eastern countries in the battle against jihadism. He has encouraged Muslims to condemn the extremists in their midst and subjected Syrian refugees to what Trump might call “extreme vetting.” He has relied on government surveillance to fight terrorism, neutralized the most alarming aspect of the threat posed by Iran, and built a reputation as a formidable terrorist hunter by using military force against jihadist leaders and operatives in a number of countries.

But even if U.S. counterterrorism policies don’t dramatically change during Trump’s presidency, the rhetoric probably will. U.S. officials will likely describe the fight against terrorism as an epic struggle, and trace the ideological roots of that terrorism to Islam and a political-religious movement within the faith that endangers Western civilization. Bush and Obama stayed away from that rhetoric in part because of their assessments of the jihadist threat. But they also did so because they worried that bolstering the clash-of-civilizations narrative would undermine their efforts to eliminate that threat. The signs so far suggest that Trump, and many of his advisers, do not share that concern.