No one yet knows who sent improvised bombs to current and former Democratic Party leaders, CNN, George Soros, and now Robert De Niro. But counterterrorism professionals are warning—tentatively—that the incendiary rhetoric from President Trump is conducive to political violence.

The mail-borne bombs may not have anything to do with anything Trump has said, though all of their intended targets appear to be critics and rivals of the president. Even if they are unrelated, there remains a danger that the atmosphere Trump’s demonizations have created will yield violence against liberals, Democrats and journalists, some former counterterrorism practitioners said.

“By publicly demonizing his perceived adversaries at rallies and social media, Trump essentially painted a target on their backs,” said Daryl Johnson, a former Department of Homeland Security analyst of far-right extremism. “We’ve seen this same technique used by extremist spokespersons and leaders to incite others toward violent action.”

The question itself is deeply discomfiting to former CIA, FBI, National Counterterrorism Center, Justice Department and Department of Homeland Security officials. All of them spent their careers assessing the relationship between terrorism and extremist figures—not the president of the United States. Similarly, all emphasized a desire to permit the FBI, Secret Service and postal inspectors to conduct their investigation.

Accordingly, several other retired senior officials promptly declined comment when The Daily Beast asked. Those willing to entertain the question did not all agree with one another, but they did consider the question of Trump’s potential moral culpability legitimate.

“When you allow this kind of permissive attitude of anger and hatred toward the media or your political opponents, that can be dangerous,” said Nada Bakos, a retired CIA counterterrorism officer. “You’re walking a fine line. You hold an office that has tremendous reach internationally and domestically.”

Ali Soufan was an FBI counterterrorism special agent with a particular expertise on al Qaeda and similar jihadist groups. “The investigation is ongoing, and of course investigators have to follow the facts and all possibilities have to be looked into thoroughly. Until then we have to be neutral, but we cannot be blind,” Soufan said.

“The inevitable consequence of violent political rhetoric is political violence, and the president is the loudest voice.”

Robert Grenier, a retired career CIA officer, headed the agency’s Counterterrorism Center during George W. Bush’s presidency. He said “the question revolves entirely around speculation” until the culprits are identified and investigators assess their motives.

“It could well be that he/she/they are inspired by presidential rhetoric, and take it more seriously than does the President himself. Could easily fall in the Henry II syndrome: ‘Will no one rid me of this turbulent priest?’” Grenier said in a text message. “I do think it’s a legitimate question—but can easily be over-done.”

In the early 1990s, Israeli prime minister Yitzhak Rabin was the subject of intense right-wing vilification by his political opponents for signing the Oslo accords intended to lead to Palestinian independence. Eventually, someone listening, Yigal Amir, assassinated Rabin in 1995.

“Rabin was assassinated at the peak of what happened in Oslo, a fanatic Jewish right extremist, because of the incitement by the rabbis and by the politicians at that time, decided that he's acting in the best interest of Israel in assassinating the prime minister,” Dror Moreh, who directed a documentary about the leaders of Israel’s Shin Bet domestic security service, reflected to NPR in 2013.

It’s too soon to know if the U.S. is in a similar situation. But Aki Peritz, a former CIA and National Counterterrorism Center analyst, was reminded of the atmosphere preceding Rabin’s assassination, even as he urged caution on presuming this week’s bomber followed Trump’s cues.

“It's not a good idea to jump to conclusions tying Presidential rhetoric to a specific, discrete terror/criminal plot without concrete evidence. For example, when bomb threats were made at dozens of Jewish Community Centers in 2017, a lot of people, including myself, assumed it was because of growing anti-Semitism in America. It turned out to be an Israeli-American guy and a journalist looking to frame his ex-girlfriend. Let's let the FBI do its job and bust this perp before trashing one's political opponents over this crime on social media,” Peritz said.

But he added: "Sustained, violent speech directed at a person or a group of people inevitably, inexorably leads to violent crimes."

Bakos, who was part of the CIA targeting team that killed al Qaeda in Iraq’s leader, said that Trump’s rhetoric has “the propensity to allow for a permissive environment for someone who is not fully engaged in rational thought” to attack the president’s rhetorical targets.

Attacks on those who might pose an institutional check on his agenda are a central aspect of Trump’s political persona.

As a candidate, he encouraged violence at his rallies by offering to pay the legal expenses of anyone who assaulted hecklers and protesters —and a recent study found cities that hosted Trump rallies saw upticks in violence afterward. His relentless campaign against what he has called the “enemies of the American people” in the media extend to praising a congressman who bodyslammed a reporter inquiring about a health care plan. What were once Trump-led chants of “lock her up” against rival Hillary Clinton, an intended recipient of one of the bombs, have now extended to other Democratic women politicians. He compared intelligence officials to Nazis for investigating his ties to Russia and described that investigation as a baseless Democratic put-up job to remove him from power, despite an array of guilty pleas and verdicts. He launched his political career on the racist lie that Barack Obama, another intended bomb recipient, was not born in the United States.

The White House has disclaimed responsibility for the bombs, with spokeswoman Sarah Huckabee Sanders claiming it is “absolutely ridiculous” to suggest a link to Trump’s rhetoric. Yet Trump on Thursday morning intimated that the “mainstream media needs to clean up its act” if it wants to avoid further bombings.

“Ultimately, our criminal justice system—even beyond terrorism—is premised on the idea that individual bad actors bear responsibility for breaking the law, and some individual or group is obviously doing that here,” said Joshua Geltzer, a former Justice Department attorney and senior director for counterterrorism on Barack Obama’s National Security Council.

“But it seems absurdly naive not to recognize that there is a broader context for even individual actions. And this is the president who, first as a candidate and even as president, has infected our political discourse with characterizations of his political opponents as criminals and of the press as an enemy of the people. He’s the president—people hear that, and it would seem foolish to suggest that might not affect what ideas people have.”