President Trump placed a wreath at the Tomb of the Unknowns on Monday and paid tribute to fallen American servicemen — including the son of Homeland Security Secretary John Kelly.

Leading solemn Memorial Day ceremonies for the first time as commander in chief, Trump told mourners at Arlington National Cemetery that Americans have a duty to honor Gold Star families every day the sun rises.

“Words cannot wipe away the tears or bring back those smiling faces. But if Americans just take the time to look into your eyes, and tell you how much we thank you, and how dearly we pray for you, and how truly we love you, then hopefully you can find solace through your pain,” Trump said.

“And every time you see the sun rise over this blessed land, please know your brave sons and daughters pushed away the night and delivered for us all that great and glorious dawn.”

Trump singled out for praise three fallen heroes killed fighting terrorists Afghanistan: Marine 1st Lt. Robert Michael Kelly, Army Spc. Christopher Horton and Army Capt. Andrew Beyers.

“We grieve with you, we honor you and we pledge to you that we will always remember Robert and what he did for all of us,” the president said.

Horton, 26, died in a firefight on Sept. 9, 2011, and Byers — a 30-year-old Army Green Beret — was killed in a clash with Taliban fighters on Nov. 3, 2016.

Kelly, 29, was the son Homeland Secretary Chief and retired Marine Gen. John Kelly. He was killed on Nov. 9, 2010, when he stepped on a land mine while leading a platoon in the town of Sangin, scene of some of the most intense fighting of the war.

Two days earlier, Secretary Kelly teared up on TV while discussing his son.

“He’s the finest man I ever knew,” Kelly said as he began to choke up with emotion on Fox News. “Wonderful guy. Wonderful husband. Wonderful son. Wonderful brother. Brave beyond all get out. His men still correspond with us. They still mourn him as we do.”

Asked on Monday what this day meant to him, Secretary Kelly replied succinctly: “Sad.”

Secretary Kelly’s other son, Johnny, is getting ready for his fifth military deployment. A son-in-law, Jake, is a wounded warrior.

Following Trump’s 20-minute address, he, Vice President Mike Pence and Kelly toured Arlington’s Section 60 — where the fallen of Afghanistan and Iraq are laid to rest.

While there, Trump left flowers at Lt. Kelly’s grave and met with several grieving families, including youngster Christian Jacobs, 6, who was dressed in a miniature replica of his late father’s uniform.

Jacobs’ dad, Marine Sgt. Christopher Jacobs, was killed during a training accident in 2011, when Christian was 8 months old.

Trump chatted with the boy and gave him a high five.

In New York, Gov. Cuomo attended three parades around the state — in Lindenhurst and Valley Stream on Long island and in Chappaqua in Westchester, where he joined local residents Bill and Hillary Clinton.

“I always enjoy marching with some of my dearest friends in the Chappaqua #MemorialDay parade,” Cuomo tweeted alongside a photo of the three.

The Clintons said they are regular attendees at the procession.

“We know people here who have lost family members in battle and it’s an important day for Americans, all of us,” the former president told WABC. “It’s one thing that ought to bring us together.”

Mayor de Blasio, meanwhile, joined hundreds of veterans and service members for a ceremony at the Intrepid Sea, Air and Space Museum.

He began with a moment of silence for the Navy SEAL skydiver who died Sunday when his chute failed to open during a Fleet Week aerial demonstration.

“I have to tell you that all of us admire the Navy SEALs,” de Blasio said. “We know sometimes Navy SEALs do things that very few others can do. It’s a shock to see this loss, but our solidarity with the SEALs is strong.”

Admiral Phil Davidson, commander of US Fleet Forces Command, reminded the assembled crowd of the meaning of Memorial Day after a 100-foot flag was unfurled on the deck of the Intrepid and four wreaths were tossed into the water.

“We need to remember the sheer scale of our war dead’s sacrifice,” he said.