Barack Obama Shares 9/11 Tribute on Twitter Recalling 'Spirit of Unity' After Terror Attacks

Former President Barack Obama shared his 9/11 tribute on Twitter, remembering the "spirit of unity" among Americans as they came to terms with the worst terror attack in the country's history.

"As we remember those we lost on 9/11, we also remember the spirit of unity and togetherness that defined the weeks and months after," Obama tweeted Tuesday. "On this day of service, I'm reflecting on all those still working to embrace that spirit, today and every day."

Obama linked to a Fox 5 NY story about dozens of volunteers from the veterans charity The Mission Continues working together with the National Park Service and Fox Sports Supports to restore and maintain Ellis Island in honor of those who died on September 11, 2001.

"9/11 is also known as one of the largest days of service across the entire country," Vu Nguyen, senior city impact manager for The Mission Continues, told Fox 5 NY.

"And in the spirit of giving back and veterans continuing to serve, coming back to a place like this to continue our service, that is a very historic, place is very meaningful for us."

Nearly 3,000 people died in the 9/11 terror attacks, orchestrated by Osama Bin Laden, chief of the al-Qaeda militant group. Most died when two planes struck the World Trade Center buildings commonly known as the Twin Towers in New York City.

Another hijacked plane struck the Pentagon, and one other plane, United Airlines Flight 93, crashed into a Pennsylvania field after passengers fought back against the terrorists on board, storming the cockpit.

The attacks triggered a chain of events that led to the Afghanistan and Iraq wars, costing many more lives in the 18 years since the planes hit the towers. Bin Laden was killed during a Navy SEAL operation at his compound in Pakistan in 2011.

"For every American who lived through that day, the September 11 attack is seared into our soul," President Donald Trump said during an event at the Pentagon to mark the 9/11 anniversary Tuesday. "It was a day filled with shock, horror, sorrow and righteous fury."

Trump told the families of 9/11 victims that he and First Lady Melania Trump "are united with you in grief."

"We come here in the knowledge that we cannot erase the pain or reverse the evil of that dark and wretched day. But we offer you all that we have: Our unwavering loyalty, our undying devotion and our eternal pledge that your loved ones will never, ever be forgotten," Trump said.

Barack Obama 9/11 September 11 attacks tribute
Former President Barack Obama speaks at a rally to support Michigan democratic candidates at Detroit Cass Tech High School on October 26, 2018 in Detroit, Michigan. Obama shared his 9/11 tribute on Twitter marking the 18th anniversary of the terror attacks in 2001. Bill Pugliano/Getty Images