As a presidential candidate, Donald Trump ventured far beyond the norms of political behavior when it came to the 9/11 terrorist attacks — blaming George W. Bush for failing to prevent the deadly assault and trafficking in bogus conspiracy theories about Muslims cheering the tragedy from rooftops.

But on Monday, in his first commemoration of the al-Qaeda attacks as president, Trump struck relatively traditional notes of resolve and patriotism.

“These are horrible, horrible enemies — enemies like we’ve never seen before,” Trump said during remarks at the Pentagon marking the 16th anniversary of the terrorist attacks in New York, Washington and Pennsylvania.

That apparently unscripted comment was as close as Trump got to applying his campaign trail catchphrase “radical Islamic terrorism” to the attacks directed by al-Qaeda leader Osama bin Laden.

Military and diplomatic leaders, among others, have discouraged such language as inflammatory and unhelpful, but Trump has continued to use it in some settings. Former Trump adviser Stephen K. Bannon’s conservative website, Breitbart News, took the president to task for the omission on Monday.

Visitors remember victims of the Sept. 11, 2001 attacks at the Pentagon Memorial in Arlington on Monday. (Bonnie Jo Mount/Washington Post)

“We’re ensuring they never again have a safe haven to launch attacks against our country,” Trump said in a brief, somber speech near the site where a hijacked jetliner slammed into the iconic five-sided Defense Department headquarters on Sept. 11, 2001. Two other planes hit and destroyed the World Trade Center, and a fourth crashed in rural Pennsylvania when passengers overpowered the hijackers.

“We are making plain to these savage killers that there is no dark corner beyond our reach, no sanctuary beyond our grasp, and nowhere to hide anywhere on this very large Earth,” he said.

Trump also did not mention his proposed temporary ban on immigration from several Muslim-majority nations, which he has said is needed to keep the United States safe from terrorism. He appeared to stick closely to a prepared text.

“The horror and anguish of that dark day were seared into our national memory forever,” Trump said of the attacks that killed nearly 3,000 people.

His own memory of the event, however, has often proved unreliable.

In November 2015, Trump claimed at a campaign event that residents of a New Jersey town with a large Muslim population had cheered as the twin towers fell.

“I watched when the World Trade Center came tumbling down,” Trump said then. “And I watched in Jersey City, New Jersey, where thousands and thousands of people were cheering as that building was coming down. Thousands of people were cheering.”

President Trump listens during a ceremony to commemorate the September 11, 2001 terrorist attacks, at the Pentagon on Monday. (Andrew Harrer/Bloomberg)

The claim has repeatedly been debunked as a hoax, including by police, but Trump stuck to it the next day in an interview on ABC’s “This Week.”

“It did happen. I saw it,” Trump said then. “It was on television. I saw it.”

Challenged, Trump added this:

“There were people that were cheering on the other side of New Jersey, where you have large Arab populations. They were cheering as the World Trade Center came down.”

The Democratic mayor of Jersey City, home to about 15,000 Muslims, tweeted at the time that “either @realDonaldTrump has memory issues or willfully distorts the truth, either of which should be concerning for the Republican Party.”

A few months later, during a Republican primary debate, Trump suggested that competitors Jeb Bush and Sen. Marco Rubio (R-Fla.) were soft on terrorism for their defense of former president George W. Bush.

“The World Trade Center came down during the reign of George Bush,” Trump said dismissively. “He kept us safe? That is not safe. That is not safe.”

Trump also blamed former Democratic president Bill Clinton for not killing bin Laden “when he had the chance” and said that Bush “had the chance, also, and he didn’t listen to the advice of his CIA.”

The moment revealed Trump’s iconoclastic willingness to criticize Republicans even as he sought to lead them, as well as his get-tough rhetoric on terrorism. Both were qualities voters prized in making him the nominee and the president.

Trump has spoken publicly about the 9/11 attacks frequently, starting long before the New York businessman became a 2016 presidential candidate. His observations and claims have ranged from empathetic to boastful to snide.

On the day of the attacks, the Queens native told New York television station WWOR that one of his buildings, 40 Wall Street, had reclaimed its position as the tallest building in Lower Manhattan. He also made false or exaggerated statements during the interview, including claiming that he witnessed people jumping to their deaths — even though the World Trade Center was more than four miles away from Trump Tower.

In 2011, he claimed to have predicted the attacks in his 2000 book “The America We Deserve.” On the 9/11 anniversary in 2013, he wrote on Twitter, “I would like to extend my best wishes to all, even the haters and losers, on this special date, September 11th.”

Trump’s tone Monday, by contrast, was inclusive and reflective.

“On that day, not only did the world change, but we all changed,” Trump said. “Our eyes were opened to the depths of the evil we face. But in that hour of darkness, we also came together with renewed purpose. Our differences never looked so small, our common bonds never felt so strong.”

Earlier, Trump led a moment of silence at the White House. Trump and first lady Melania Trump walked onto the South Lawn and stood as bells tolled. They then bowed their heads and stood silently before placing their hands on their hearts as a bugler played taps.

Trump, a frequent early morning tweeter, did not post any messages ahead of the 8:46 a.m. ceremony at the White House. In the afternoon, he posted a Twitter montage of images of him and Melania Trump during both events.

“May God Forever Bless the United States of America,” Trump tweeted, adding the hashtag, “#NeverForget911.”

Former National Security Council legal adviser John B. Bellinger III, who was in the White House Situation Room during the attacks and had criticized Trump’s national-security credentials during the campaign, praised his handling of Monday’s ceremonies.

“President Trump’s moment of silence at the White House and remarks at the Pentagon were sober and presidential,” Bellinger said. “His remarks were well-written, and he stuck to them and steered clear of anything political or divisive.”