MARGRATEN, Netherlands (AP) — Dutch Prime Minister Mark Rutte paid tribute Sunday at a Memorial Day ceremony to U.S. troops who fought and died liberating the Netherlands from Nazi occupation in World War II, while NATO's supreme commander said the fight to defend freedom continues to this day.

Thousands of people sat under blue skies and wispy white clouds for Sunday's ceremony at the American cemetery in Margraten, a manicured patch of 65.5 acres (26.5 hectares) in the rolling hills of the southern province of Limburg that contains 8,301 headstones.

The cemetery is on land close to the Dutch border with Germany that was liberated from Nazi occupation on Sept. 13, 1944, by the U.S. 30th Infantry Division.

"We say thank you to our liberators," Rutte said. "Thank you for enabling us to stand here today in freedom, and we bow our heads in memory of the fallen."

Among the thousands of people attending the solemn ceremony were orphans of soldiers who were buried or are listed as missing at Margraten.

Arthur Chotin, whose father was killed in a jeep accident in the aftermath of the war and is buried at Margraten, thanked Dutch families who have adopted all of the graves at the cemetery, helping to keep alive the memory of the dead.

"Even though I didn't know him, I think of him almost every day. What he missed and what my mother and I missed," Chotin said. "So here I am. 70 years old, more than twice the age of the father I never played catch with, never argued with, never even hugged. And the single thought in my mind today is that I hope he would be proud of me.

"Oh, the power these dead have over those they left behind."

NATO's supreme commander, U.S. Air Force Gen. Philip Breedlove, reminded the crowd that the freedom Allied soldiers died defending in World War II cannot be taken for granted. "Recent world events have shown us the concept of armed conflict in Europe remains possible," he said.

"We must be vigilant if we are going to preserve democracy and freedom," Breedlove said. "It is important that we celebrate the courage of the youth of yesterday but we must also support the youth of today as our service members continue to defend the values forever enshrined here."