U.S. officials who’ve been working to refute terrorist propaganda and blunt recruitment by ISIS and other groups are bracing for a Donald Trump administration, fearing that he and his advisers could set back their efforts by years and play into terrorists’ hands.

Three U.S. officials told The Daily Beast that President-elect Trump’s campaign rhetoric, combined with the names now surfacing as potential top national security advisers in the next administration, signal a dramatically different approach that could give ISIS ammunition to claim that the United States is engaged in a religious war.

In fact, ISIS commanders have already begun to make that argument. “ This guy [Trump] is a complete maniac ,” Abu Omar Khorasani, an ISIS leader in Afghanistan, told Reuters. “His utter hate towards Muslims will make our job much easier because we can recruit thousands.”

During the campaign, Trump pledged to ban Muslims from entering the United States, a position he later modified to what he described as “extreme vetting” of individuals from certain countries. But he also excoriated his rival, Secretary of State Hillary Clinton, as well as President Obama and his aides for refusing to use the words “radical Islamic terrorism” to describe groups like ISIS.

Clinton agreed eventually to utter the term, saying the words didn’t matter much. But her earlier decision to avoid such language was deliberate and informed by many conversations that administration officials had with Muslim leaders and community groups, who concluded that linking terrorists’ activities with a religion only served to legitimize them in the eyes of impressionable recruits.

Equating radical terrorism with Islam was not only inaccurate, it was “not very helpful if we are talking about a lasting ISIS defeat,” one defense official told The Daily Beast, adding that it allows the terror group to claim that it is defending Muslims everywhere. “They will say, ‘Join us. America has declared war on Islam.’”

“Of course we are concerned,” a second official said of the heated rhetoric on the campaign trail that is now apparently transferring into the next administration. The official noted that the U.S. military is making demonstrable progress on the battlefield against ISIS but that those gains could be offset by recruitment efforts given a new boost from incoming administration officials.

The names surfacing as likely to play a key role in advising the next president have been a cause of alarm for some officials and experts. Retired Gen. Michael Flynn, who ran the Defense Intelligence Agency and was one of the first intelligence leaders to identify ISIS as a bigger threat than the Obama administration thought, has become a vocal critic of the administration’s language and its counterterrorism efforts.

Flynn has said “political correctness” has prevented the United States from confronting violent extremism, which he sees as a “cancerous idea that exists inside of the Islamic religion.” Flynn authored a book that argued the U.S. government “has concealed the actions of terrorists like [Osama] bin Laden and groups like ISIS, and the role of Iran in the rise of radical Islam…” And his Twitter feed has linked to video describing “fear of Islam” as a “rational” reaction to terrorist attacks.

Another adviser to Trump’s national security transition team, Clare Lopez, is known within foreign policy circles for her claims that the U.S. government has been infiltrated by agents from the Muslim Brotherhood. Lopez co-authored a book, See No Sharia, which purports to show how “Islamists in general and the Muslim Brotherhood in particular have gained access to and considerable sway over policymakers in the White House, the FBI and the Departments of State, Justice, Defense and Homeland Security.”

Lopez has also espoused the opinion—widely discredited—that terrorists short-selling U.S. stocks caused of the 2008 financial collapse. The crisis was actually precipitated by a collapse in the real-estate market and the proliferation of exotic financial products manufactured by U.S. financial institutions.

Tuesday, the Wall Street Journal reported that Frank Gaffney, who regularly warns of the looming imposition of sharia law in the United States and has accused anti-tax conservative Grover Noquist of being secretly aligned with the Muslim Brotherhood, was joining the transition team to assist on national security issues. And Kansas Secretary of State Kris Kobach, a member of the transition team's immigration policy group, has reportedly been discussing a registry for immigrants from Muslim countries.

The combination of campaign rhetoric and fringe views of some key Trump advisers portends a radically different approach to fighting terrorism, experts said.

“The Bush and Obama administrations agreed that the key to defeating jihadist recruitment is to carefully distinguish between jihadists and mainstream Muslims,” William McCants, a senior fellow at the Brookings Institution and the author of The ISIS Apocalypse: The History, Strategy, and Doomsday Vision of the Islamic State, told The Daily Beast. “The rhetoric and policies put forward by Trump and his top advisers during the campaign collapsed that distinction, which will make us all less safe because it gives credence to jihadist propaganda that the United States is at war with Islam.”

In the past week, every time a potential Trump administration nominee is mentioned, the name flutters through the Pentagon and around U.S. intelligence and security agencies, where officials try to game out how it might help or hurt the ongoing campaign against ISIS and al Qaeda.

The perception that Islam is under attack would allow terror groups to resurge in Sunni Arab-dominated cities in Iraq and Syria where ISIS appears to be on the decline, two defense officials told The Daily Beast. The best military campaign against jihadism is not a long-term plan, defense officials have repeatedly said; it only works if there is no political room for groups like ISIS and al Qaeda to return.

In the past two days, former New York mayor Rudy Giuliani and John Bolton, the one-time U.S. ambassador to the United Nations, have been discussed as the next secretary of state. Giuliani, who has no direct foreign policy experience, falsely said during the campaign that terrorist attacks on U.S. soil only occurred under the presidencies of Obama and Bill Clinton, skipping over the 9/11 attacks, which occurred when he was the mayor of New York. Bolton has called for U.S. support of Egyptian President Abdel Fatteh el-Sisi, whose authoritarian rule, particularly in the northern Sinai, has become a recruiting tool for jihadists in northern Africa.

Privately, U.S. officials told The Daily Beast that they were concerned a Trump administration would seek to dismantle new programs set up in federal agencies specifically designed to work with mosques and community groups around the country.

In January, the Obama administration established a task force for “countering violent extremism,” led by the Department of Homeland Security, that includes more than 10 agencies and departments from across the government. It mission is to work with local leaders and community groups in order to de-legitimize the ISIS’s and other terrorist groups’ apocalyptic vision. Experts in the field generally agreed that the approach was more helpful than many of the fitful, often tone-deaf attempts to lure Muslims from the jihadists’ siren song.

Since 2012, the federal government has held thousands of meeting and “community engagements” in U.S. cities, including roundtable discussions, town hall meetings, and meetings with community leaders.

“To be successful in our homeland security efforts, we have to underscore and reinforce the fact that ISIL does not represent Islam and cannot justify its barbaric terrorism with twisted interpretations of one of the world’s most prominent religions,” George Selim, the director of the department’s office for community partnerships, told a House committee in September. (ISIL is the acronym the Obama administration uses for the terror group.)

A new report on global efforts to combat violent extremism, released Tuesday, encouraged such programs and called on the United States and other countries “to avoid rhetoric and responses that estrange Muslim communities.”

“In the United States, such an approach would necessitate redoubling efforts to engage with Muslim communities and address their concerns about stigmatization, surveillance, entrapment, and hate crimes,” said the report, co-authored by former CIA director and secretary of defense Leon Panetta and former British prime minister Tony Blair, and published by the Center for Strategic and International Studies.

McCants said the Trump administration should survey current homeland security and counterterrorism efforts and hear from a broader range of experts than appears to be shaping policy now.

“My hope is that the incoming administration will change its mind after talking to America’s partners and allies in Europe and the Middle East, who are keen to isolate our jihadist enemies rather than enlarging their ranks. President-elect Trump needs to hear from more than just a few paranoid voices who profit politically or professionally by stoking American fears of Islam,” McCants said.