WASHINGTON >> President Joe Biden, whose elder son Beau died of cancer years after deploying to Iraq, signed legislation on Wednesday expanding federal health care services for millions of veterans who served at military bases where toxic smoke billowed from huge burn pits.

“We owe you,” Biden said. “You’re the backbone. You’re the steel. You’re the sinew. You’re the very fiber that makes this country what it is.”

The law, which Biden described as long overdue, caps a yearslong battle to ensure treatment for chronic illnesses that veterans have blamed on burn pits, which were used to dispose of chemicals, tires, plastics, medical equipment and human waste on military bases. Estimates of affected troops run to 3.5 million.

It reflected the struggles of military families — and the president’s personal experience. It was the most direct link the president has publicly drawn between Beau’s fatal brain cancer and burn pits.

— The Associated Press