Luis Rivera-Pérez was a baby-faced 18-year-old recruit when he left his home in San Juan in 1951 to fight in Korea with the 65th Infantry Regiment, a storied Puerto Rican unit known as the Borinqueneers. He aged quickly in combat, venturing out on night patrols where they used flamethrowers to incinerate enemy troops hidden in caves. In one battle, they slogged up a hillside for a bayonet assault, only to be pinned down by relentless gunfire.

“It was a massacre,” said Mr. Rivera-Pérez, 84. “There were so many wounded and dead.”

He was among a group of Borinqueneers — a name rooted in the island’s past — who were pinned down again this week, this time in a hotel in a drab industrial corner near Kennedy International Airport in Queens. They were en route to Puerto Rico from South Korea, where they had been honored by its government for their military service, when Hurricane Maria devastated their island home, leaving them stranded with little word from relatives and friends.

Just as scarce was encouragement from President Trump, their commander in chief, who has been faulted by many for spending more time attacking football players exercising their constitutional right to peaceful protest than addressing the mounting humanitarian crisis. They were flabbergasted when the president’s first substantive remarks about the tragedy was how the island “sadly” had to deal with the $73 billion debt it owes hedge funds and banks. They felt it was an insult to them — American citizens by act of Congress and birth — who felt they had already paid a steep price in blood and youth decades ago.

Indeed, this fighting force — lauded by no less than Gen. Douglas MacArthur — has seen action from World War I through Korea, and was among the last of the segregated military unit to be disbanded. Their bravery and sacrifice is chronicled in citations, medals and etched on headstones and remembered in street names and on postage stamps. On their recent South Korea trip, strangers stopped them on the street to offer thanks and gratitude.