Across conservative media, these accusations grew into a fable that President Barack Obama had freed five Afghan terrorists for a single white-skinned jihadi. (In 2018, the Trump administration would invite the same five Taliban members to peace talks in Doha, Qatar.) Within days of his recovery, Bergdahl’s Idaho hometown canceled its celebration in his honor, and his parents were put under FBI protection amid a swarm of death threats.

Grenell didn’t keep his connection to the platoon secret. He tweeted that his firm was working for the soldiers “pro bono.“ But in hindsight, it would be more accurate to say the soldiers were working for him—a Republican strategist promoting a useful political narrative months before the 2014 midterms. When my co-author and I conducted research for our book, some of Bergdahl’s platoonmates sang Grenell’s praises and assured us the same thing he had assured them: There was nothing political about his work on their behalf.

In fact, Grenell, intentionally or not, had delivered on a promise made by GOP congressional aides two years earlier: If Obama went through with the prisoner trade, the aides told State Department officials in a closed-door briefing, Republicans had a plan to turn it into his “Willie Horton moment” in the war on terror. That threat, first reported by the late Rolling Stone reporter Michael Hastings, held true, as conservative media outlets and Republicans in Congress seized the prisoner swap as a defining White House scandal. Three weeks after the Bergdahl exchange, Obama’s disapproval rating hit 55 percent, the highest of his presidency.

Trump, as he prepared for his 2016 presidential campaign, recycled the charge of treason and said Bergdahl “should have been executed.” We may never know whether Grenell took his cues for the smear campaign from the platoon’s own rumor mill or from some other source. But the idea that Bergdahl wanted to join the Taliban can be traced to the Taliban itself. In August 2010, nearly four years before Grenell’s Fox hit, a Taliban commander had met with a British journalist to share what seemed like a sensational war zone scoop. The Taliban wanted the world to know Bergdahl had converted to Islam, changed his name to Abdullah, and was teaching bomb-making seminars to the rank and file. The Sunday Times headline—“Captured U.S. Soldier Has Joined Our Cause, Say Taliban”—quickly circled the globe.

The Pentagon never charged Bergdahl with treason; it never found any evidence he was “sympathetic to the Taliban,” as the Army general in charge of the investigation said. Bergdahl testified that he had left his post so he could walk to another base, where he hoped to report leadership problems in his unit—a claim the Army’s investigation found credible while deeming Bergdahl’s plans profoundly unrealistic. (In October 2017, Bergdahl pleaded guilty to desertion and misbehavior before the enemy, for which he received a dishonorable discharge, reduction in rank to private and a fine of $10,000.) The Sunday Times journalist, Miles Amoore, told me he realized he had been conned by the Taliban and had bought into a story that was false.

But Trump had little use for the truth. Bergdahl—traumatized from five years in solitary confinement, more than three of which he spent in a steel cage—was a perfect target for the real estate mogul’s nascent presidential campaign. (Trump, recall, prefers “people who weren’t captured.”) He called Bergdahl a traitor dozens of times and continued to accuse him of treason, a lie amplified not only by hoots and hollers at his rallies but by an army of social media supporters and trolls. As we report in our book, researchers at Clemson University in 2018 tracked Bergdahl-as-traitor memes to Twitter accounts from the Internet Research Agency in St. Petersburg, where Russians, like Trump and Grenell—and the Taliban before them—understood “Abdullah Bergdahl’s” enduring value as propaganda.

In 2017, I had the chance to ask Roger Stone, Trump’s longtime political adviser—who was recently sentenced to more than three years in prison for lying to Congress and witness tampering in the Mueller investigation—what he knew about Grenell and whether anyone had tasked him to run the Bergdahl smear. Stone didn’t know. He refused to work with Grenell, he told me, because he found him “too shady.”

Grenell, for his part, did not respond to requests for comment for our book or, in more recent days, for this article.

Grenell’s record of spreading misinformation extends beyond the Bergdahl case. In October 2016, in the midst of brazen Russian election meddling, he published a Fox News column assuring Americans that nothing unusual was happening. “Reports that Russia is trying to influence the 2016 presidential elections [are] unfolding in many political newsrooms like it’s a new occurrence,” he wrote. “Russian or Russian-approved tactics like cyber warfare and campaigns of misinformation have been happening for decades.” The real victim of Russian aggression wasn’t the American election, Grenell wrote, but a Moldovan oligarch named Vladimir Plahotniuc. (Grenell did not reveal, as ProPublica recently reported, that Plahotniuc had been paying him that year as a consultant; a lawyer for Grenell disputed the report.)

Now that he oversees 17 intelligence agencies across several departments, Grenell wields immense influence. If there is such a thing as the deep state, he is in charge of it. In an election year, after an impeachment trial that centered on the solicitation of foreign influence in U.S. elections, there is a legitimate fear that Grenell will turn elements of the national security apparatus into a de facto arm of the Trump campaign.

His record suggests Americans should be worried that disinformation will appear not just on Facebook and Twitter but in official government reports. If Grenell wants to spin intelligence in the service of his party or use foreign propaganda to fill the President’s Daily Briefing, there’s little standing in his way. With Bergdahl as their template, Trump and Grenell already know how this game works.