NEW YORK >> From an urban memorial to a remote field to the heart of of the nation’s military might, President Joe Biden today paid tribute at three hallowed places of grief and remembrance to honor the lives lost two decades ago in the 9/11 terror attacks.

The solemn day of commemoration offered frequent reminders for Americans of a time when they united in the face of unimaginable tragedy. That fading spirit of 9/11 was invoked most forcefully by the president at the time of the attacks, George W. Bush, who said, “That is the America I know,” in stark contrast to the bitterly divided nation Biden now leads.

Biden left the speech-making to others, paying his respects at the trio of sites in New York, Pennsylvania and outside Washington where four hijacked planes crashed on Sept. 11, 2001, killing nearly 3,000 people, shattering the nation’s sense of security and launching the country into two decades of warfare.

Biden wiped away a tear as he stood in silence at the site where the World Trade Center towers fell, and looked up at the haunting sound of a jet plane under clear blue skies reminiscent of that fateful day.

In a grassy field in Pennsylvania, Biden comforted family members gathered at a stone boulder near Shanksville that marked where passengers brought down a hijacked plane that had been headed for the nation’s capital. At the Pentagon, Biden and his wife, Jill, took a moment of silence before a wreath studded with white, purple and red flowers on display in front of the memorial benches that mark the victims of the attack at the military headquarters.

Delivering Bud Light and appreciation to the Shanksville Volunteer Fire Department, which responded to the crash of United Flight 93, Biden praised Bush’s comments in his only public remarks of the day, saying the Republican “made a really good speech today – genuinely,” and wondered aloud what those who died that day would think of today’s rancor.

Gesturing to a cross-shaped memorial made of steel from the twin towers adjacent to the firehouse, Biden reflected: “I’m thinking what, what what would the people who died, what would they be thinking. Would they think this makes sense for us to be doing this kind of thing where you ride down the street and someone has a sign saying ‘f- so-and-so?’”

It was a reference to an explicit sign attacking Biden last week in New Jersey as he toured storm damage that was displayed by supporters of former President Donald Trump. Biden expressed incredulity at recent comments by Trump, whom he accused of abandoning the nation’s ideals during his time in office.

“Everyone says, ‘Biden, why do you keep insisting on trying to bring the country together?’’’ the president told reporters. “That’s the thing that’s going to affect our well-being more than anything else.”

In a frequent refrain of his presidency warning of the rise of autocracies, he added, “Are we going to, in the next four, five, six, ten years, demonstrate that democracies can work, or not?”

At ground zero in New York City, Biden stood side by side with former Presidents Barack Obama and Bill Clinton at the National September 11 Memorial as the names of the dead were read aloud by their loved ones. Each man wore a blue ribbon and held his hand over his heart as a procession marched a flag through the memorial before hundreds of people, some carrying photos of loved ones lost in the attacks.

Bush, delivering the keynote address in Shanksville, lamented that “so much of our politics have become a naked appeal to anger, fear and resentment.”

“On America’s day of trial and grief, I saw millions of people instinctively grab for a neighbor’s hand, and rally for the cause of one another,” Bush said. “That is the America I know.”

Alluding to domestic turmoil, including the Jan. 6 insurrection at the Capitol, Bush said that “the dangers to our country can come not only across borders but from violence that gathers within.” He added that while they have little cultural similarity to the 9/11 attackers, “they are children of the same foul spirit, and it is our continuing duty to confront them.”

Vice President Kamala Harris also spoke at the Flight 93 National Memorial, echoing the theme of unity as she praised the courage of those passengers and the resilience of Americans who came together in the days after the attacks.

“In a time of outright terror, we turned toward each other,” Harris said. “If we do the hard work of working together as Americans, if we remain united in purpose, we will be prepared for whatever comes next.”

Biden was a U.S. senator when hijackers commandeered four planes and carried out the attacks. He was Obama’s vice president in 2011 when the country observed the 10th anniversary of the strikes. Saturday’s commemoration was his first as commander in chief.

It is now Biden who shoulders the responsibility borne by his predecessors to prevent another strike. He must do that against fears of a rise in terrorism after the hasty U.S. withdrawal from Afghanistan, where those who planned the Sept. 11 attacks were sheltered.

In remarks at the firehouse Biden defended the withdrawal, which culminated with a massive airlift to evacuate more than 110,000 Americans and allies — but still resulted in many being left behind for an uncertain future under Taliban rule.

“Could al-Qaida come back? Yeah. But guess what, it’s already back other places,” Biden said. “What’s the strategy? Every place where al-Qaida is, we’re going to invade and have troops stay in? Cmon.”

Rather than deliver formal remarks, Biden released a taped address late Friday about the anniversary in which he spoke about the “true sense of national unity” that emerged after the attacks, seen in “heroism everywhere — in places expected and unexpected.”

“To me that’s the central lesson of Sept. 11,” he said. “Unity is our greatest strength.”

Biden became the fourth president to console the nation on the anniversary of that dark day, one that has shaped many of the most consequential domestic and foreign policy decisions made by the chief executives over the past two decades.

Trump skipped the official 9/11 memorial ceremonies and instead visited a fire station and police precinct in New York, where he laced into Biden over his withdrawal from Afghanistan and repeated lies about the 2020 election as he paid tribute to New York’s first responders.

Bush was reading a book to Florida schoolchildren when the planes slammed into the World Trade Center. He spent that day being kept out of Washington for security reasons — a decision then-Sen. Biden urged him to reconsider, the current president has written — and then delivered a brief, halting speech that night from the White House to a terrified nation.

The terrorist attack would define Bush’s presidency. The following year, he chose Ellis Island as the location to deliver his first anniversary address, the Statue of Liberty over his shoulder as he pledged, “What our enemies have begun, we will finish.”

The wars in Iraq and Afghanistan were still deadly when Obama visited the Pentagon to mark his first Sept. 11 in office in 2009.

By the time Obama spoke at the 10th anniversary, attack mastermind Osama bin Laden was dead, killed in a May 2011 Navy SEAL raid. Though the nation remained entangled overseas, and vigilant against threats, the anniversary became more about healing.

Trump pledged to get the U.S. out of Afghanistan, but his words during his first Sept. 11 anniversary ceremony in 2017 were a vivid warning to terrorists, telling “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.”