It is the most fateful moment in a movie that purports to present a searingly accurate account of the 2012 attacks that left four Americans dead in Benghazi, Libya: a scene in which the highest-ranking CIA operative at a secret agency compound orders his security team to “stand down” rather than rush off to rescue U.S. diplomats under siege less than a mile away.

According to the officer in charge of the CIA’s Benghazi base that night, the scene in the movie is entirely untrue.

“There never was a stand-down order,” said the base chief known as Bob, speaking publicly for the first time. “At no time did I ever second-guess that the team would depart.”

Nor, he said, did he say anything that could be “interpreted as equivalent” to an order to stand down.

In a lengthy interview with reporters from The Washington Post, Bob provided new details about the attacks and his interactions with J. Christopher Stevens, the U.S. ambassador to Libya who perished in them.

The account from the CIA base chief adds a critical and previously missing voice to the public record on Benghazi, an attack that even three years later remains so politically charged that Sen. Ted Cruz (Tex.), a Republican presidential candidate, made it the center of his closing remarks during this week’s GOP debate.

The question of whether someone issued a “stand down” has loomed over Benghazi since the immediate aftermath of the attacks. The initial speculation centered mainly on whether an official in Washington, including then-Secretary of State Hillary Clinton, had impeded rescue attempts — an allegation rejected by a series of congressional inquiries. A 2014 House Intelligence Committee report found “no evidence that there was either a stand down order or a denial of available air support.”

Bob agreed to talk on the condition that his last name not be used because even though he has retired, his cover has not been lifted. “I thought I would regret it if I didn’t,” he said about finally speaking out. “So much of this information has been wrong.”

The movie, “13 Hours: The Secret Soldiers of Benghazi,” is based on a book co-written by U.S. contractors hired to protect the CIA base in Benghazi. Bob said he was familiar with the contents of the book but had not seen the movie, which opened Friday. Scenes from the film were described to him by a Post reporter.

The book and film blame Bob for blocking the departure of security operators until it was too late. The author of the book, Mitchell Zuckoff, said in a telephone interview that he stands by the depiction and that it is based on first-hand accounts.

“I think the evidence is extremely strong that the guys’ account is far more credible” than that of the CIA chief, Zuckoff said. He said he made multiple requests through the CIA to speak with Bob but that those requests were denied.

Zuckoff said he had numerous conversations with the CIA office of public affairs about the project, but officials said those talks came only after a draft of the book was finished and focused on whether it disclosed classified material that contractors were obligated to protect. The agency also met with the director of the film, Michael Bay, and cited a list of concerns about the contents of the book and movie script, officials said.

The book publishers bypassed the CIA clearance process typically required for works by current or former employees and contractors. Zuckoff said that was in part because the agency did not want the authors to attach their real names to the book, and that doing so would have undermined its credibility.

The book and movie render an unflattering portrait of the CIA and Bob, a former Army medic who spent 32 years with the agency.

“No one will mistake this movie for a documentary,” CIA spokesman Ryan Trapani said. “It’s a distortion of the events and people who served in Benghazi that night. It’s shameful that, in order to highlight the heroism of some, those responsible for the movie felt the need to denigrate the courage of other Americans who served in harm’s way.”

Libya wasn’t Bob’s first war zone. The former veteran case officer, now in his early 60s, spent time in Central America, Iraq and Afghanistan as a clandestine case officer assigned to the Latin America and Near East divisions.

A rumpled figure with short gray whiskers on his face, Bob said he arrived in Benghazi as base chief in December 2011. Under his command were the security team, known inside the agency as the Global Response Staff, as well as contract case officers with military experience and other U.S. personnel.

The book accuses Bob of treating the GRS contractors like “Wal-Mart security guards.” He said that is a “distortion,” describing the security team as highly accomplished. “These guys were heroes,” he said.

Bob met with Stevens on Sept. 10, 2012, when the CIA briefed the ambassador at the diplomatic facility shortly after his arrival from Tripoli. “We did try to convey the seriousness of the terrorism environment in eastern Libya,” he said.

Although there was no specific threat information against Stevens, Bob said he was already familiar with two men later implicated in the assaults on U.S. facilities: Ahmed Abu Khattala, who was charged with plotting the attacks and has been brought to the United States to stand trial, and Sufian bin Qumu, a former detainee at Guantanamo Bay who remains in Libya.

Bob said he first heard gunfire about 9:42 p.m. and suspected immediately that the diplomatic compound was under attack. The handful of U.S. diplomatic security personnel there also alerted the base and the U.S. Embassy in Tripoli.

Bob said he began calling Libyan groups and making an effort to “help get eyes up,” a reference to surveillance drones that were directed toward the compound. He said the base immediately “went into collect mode to try to figure out what was happening to the ambassador” and said Stevens’s rescue was always a priority.

According to the book and the movie, the security contractors assembled their weapons and jumped into vehicles to begin a rescue mission. Bob, they said, ordered them to wait.

Bob acknowledged that he was “concerned about an ambush” and that a departure by the security team would have “left our base more vulnerable to attack.” But, he said, “there was never any question that there was going to be a rescue mission” and no instruction by him to hold off.

Instead, Bob said he spent much of the immediate period after the attack began, about 20 minutes, standing beside the leader of the GRS team — who still works at the CIA — scrambling to enlist local security teams.

One of the things he wanted was a gun truck and support. “Technicals,” Bob said. The militias they contacted were evasive. One offered to shelter the U.S. personnel at a nearby militia compound, Bob said, while others “didn’t necessarily want to help us, and some just didn’t know what to do.”

When the team leader realized reinforcements weren’t coming, “he left” with the contractors. “If there was any delay, it was a matter of minutes. It took a good 15 to 17 minutes just to get ready,” Bob said.

About 10:03 p.m., according to a congressional timeline, the CIA security contractors left for the diplomatic compound. More than 40 minutes later, after parking some distance away and approaching on foot with weapons drawn, they arrived at the facility. Stevens was missing, and Sean Smith, a State Department communications expert, was dead from smoke inhalation inside the diplomatic villa. The attackers were gone.

A second CIA officer at Benghazi that evening backed Bob’s account. In an email provided to The Post, the officer said that “when asked if the security team could respond to the requests for assistance at the special mission compound by the security team leader, the chief of base responded with one word: ‘Absolutely.’ ”

In an email, Zuckoff said that two of the CIA security contractors “heard Bob say” stand down. He added that the base chief’s account should “be seen through the lens of hindsight. It must be terrible for him to live with the fact that he delayed the departure, knowing that the deaths [of Stevens and Smith] were caused by smoke inhalation, which by definition is a function of time.”

Other former CIA officers with no direct knowledge of the case but with experience in war zones chafed at such second-guessing and said seeking reinforcements was the right course. “Did he lose 20 minutes? Probably,” said one former senior agency official. “But that was probably the right solution.”

Eventually, all of the Americans fled the compound and headed back to the CIA base.

“A good part of the night was trying to find out where the ambassador was and what had happened to him,” Bob said.

The CIA eventually learned that Libyans had located Stevens’s body and taken it to a hospital.

The other major controversy surrounding Benghazi has focused on how the attack on the diplomatic compound was initially portrayed by the White House as a violent protest rather than a terrorist attack.

Bob said there was “some reporting” even in the midst of the attacks that a terrorist group known as Ansar al-Sharia was involved, but he said he played no role in shaping White House talking points about the attacks that came under harsh criticism.

Bob said he took only one call that evening from CIA headquarters and that it lasted two minutes. “I just cut it short,” he said. He declined to comment on continued political fighting in Washington over the attack.

The following day, about 5:15 a.m., the CIA base came under mortar fire, and two GRS operators, Glen Doherty and Tyrone Woods, were killed.

The Americans finally evacuated the CIA base at dawn, escorted by a Libyan militia convoy to the airport. Bob said they destroyed the base’s computer hard drives before they left.

The movie shows Bob wanting to stay behind to collect intelligence and depicts one of the security contractors asking, “For what, so more guys like [the two contractors killed] have to save your ass again?”

“That never happened,” Bob said. Eyebrows raised, he asked, “I was going to stay behind by myself?”

While the CIA security operators who had been so dismissive of Bob left the country, the base chief stayed in Libya, relocating to Tripoli.

“We were there to collect and find out who had attacked us,” he said.

Bob said he also returned to the CIA base in Benghazi weeks later.

“I remember every second of it,” he said. “We had lost two brave Americans on the roof at that facility. It was difficult.”

Karen DeYoung and Julie Tate contributed to this report.