WASHINGTON, D.C. (AP) – Americans from Washington to California marked Memorial Day with parades, barbecues and somber reflection in a holiday infused with fresh meaning by the approaching 10th anniversary of the Sept. 11 terrorist attacks.

The National Memorial Day Parade in Washington honored veterans and America’s war dead but also featured special tributes to Sept. 11 first responders, victims and their families. The holiday comes less than a month after U.S. Navy SEALs shot and killed Osama bin Laden, who masterminded the attacks.

Elsewhere, military jets thundered through the sky above New York after a wreath-laying ceremony aboard an aircraft carrier that’s been turned into a museum, while hundreds of volunteers put small flags on the 25,000 graves at a sprawling military cemetery near Las Vegas. U.S. troops fighting in Afghanistan also took time out to remember fallen comrades.

Along the parade route in Washington, children sat on parents’ shoulders and throngs cheered as high marching bands and floats passed. Special guests included Medal of Honor recipients, astronaut and Korean War veteran Buzz Aldrin and actor Gary Sinise, a veterans advocate who played Lt. Dan in the film ‘‘Forrest Gump.’’

Hamilton Peterson, who lost his father and stepmother when the hijacked United Airlines 93 crashed into a field in Shanksville, Pa., said the looming anniversary of the terror attacks should inspire Americans to be vigilant.

‘‘Obviously, bin Laden’s death is a highlight of the 10th anniversary. However, we recognize that future attacks are imminent and that, absent using 9/11 as a model for how to respond, all Americans need to get involved. It can’t just be the military,’’ the 51-year-old said.

Sgt. James Patrick McMichael of the Arlington County, Va., sheriff’s office was part of a team of first responders to the Pentagon. He said that even though the looming anniversary was dredging up painful memories, it was still critical that the public remember what occurred.

A commercial jet crashed into the Pentagon on Sept. 11, killing 184 people at the sprawling Defense Department headquarters.

‘‘Reliving the event is not something that I look forward to, but I don’t think it should be something that’s not brought up to the public,’’ said McMichael, who attended the parade in Washington. ‘‘I don’t think people should forget about what occurred.’’

President Barack Obama participated in a wreath-laying ceremony at the Tomb of the Unknowns at Arlington National Cemetery.

‘‘Our nation owes a debt to its fallen heroes that we can never fully repay, but we can honor their sacrifice,’’ Obama said at a Memorial Day service at the cemetery. ‘‘And we must.’’

Meanwhile, U.S. troops fighting in Afghanistan paused for Memorial Day services, with some praying and holding flag-raising ceremonies to recognize the more than 1,400 who have been killed in combat there since the war began a decade ago.

Obama plans to draw down U.S. troops in Afghanistan beginning in July, while NATO has committed to handing over control of security in the country to Afghans by 2014. For now, though, the war continues.

‘‘We reflect on those who have gone before us. We reflect on their service and their sacrifice on behalf of our great nation,’’ said Brig. Gen. Lewis A. Craparotta, who commands a Marine division in Afghanistan’s southern Helmand province. ‘‘We should also remember those serving today who embody that same commitment of service and sacrifice.’’