There are many ways to measure the cost of U.S. involvement in the Vietnam War: In bombs (7 million tons), in dollars ($760 billion in today's dollars) and in bodies (58,220).

Then there’s the price of caring for those who survived: Each year, the Department of Veterans Affairs spends more than $23 billion compensating Vietnam-era veterans for disabilities linked to their military service — a repayment of a debt that’s supported by most Americans.

But what if the casualties don’t end there?

The question has been at the heart of reporting by The Virginian-Pilot and ProPublica over the past 18 months as we’ve sought to reexamine the lingering consequences of Agent Orange, the toxic herbicide sprayed by the millions of gallons over Vietnam.

We’ve written about ailing Navy veterans fighting to prove they were exposed to the chemicals off Vietnam’s coast. About widows left to battle the VA for benefits after their husbands died of brain cancer. About scores of children who struggle with strange, debilitating health problems and wonder if the herbicide that sickened their fathers has also affected them.

Along the way, we noticed some themes: For decades, the federal government has resisted addressing these issues, which could ultimately cost billions of dollars in new disability claims. When science does suggest a connection, the VA has hesitated to take action, instead weighing political and financial costs. And in some cases, officials have turned to a known skeptic of Agent Orange’s deadly effects to guide the VA’s decisions.

Frustrated vets summarize the VA’s position this way: “Delay, deny, wait till I die.”

This month, after repeated recommendations by federal scientific advisory panels, Congress passed a bill directing the VA to pursue research into toxic exposures and their potential effects across generations. But even that will take years to produce results, years some ailing vets don’t have.

The questions we’ve posed have no easy answers. But science — and our own analysis of internal VA data — increasingly points to the possibility that Agent Orange exposure might have led to health problems in the children of veterans. And we can’t help but think of the words displayed at the entrance to the VA headquarters in Washington: “To care for him who shall have borne the battle and for his widow, and his orphan.”

We noticed the phrase, a quote from Abraham Lincoln’s second inaugural address, during an evening stroll through D.C. in June, a day before hosting a forum on Agent Orange’s generational effects and policy implications. With us that night was Stephen M. Katz, the Virginian-Pilot photographer who initiated our reporting project when he shared the story of his estranged father, a Vietnam vet who’d gotten back in touch to warn that he’d sprayed Agent Orange.

Does the VA’s motto apply to Katz? His brother born before the war is healthy. At 46, Katz suffers from myriad health problems, including a heart defect, type-2 diabetes, an underactive thyroid, immune and endocrine deficiencies, and a nerve disorder that severely limits the use of his right hand.

What about the thousands of other children of Vietnam veterans who shared their stories with us over the past year? What about the children of Gulf War veterans exposed to depleted uranium? The children of Iraq and Afghanistan war veterans exposed to toxic burn pits? The children of future service members exposed to yet unknown toxins on the modern battlefield?

What responsibility — if any — does a nation have to those who weren’t drafted into service, but who may have been harmed nonetheless?

The Agent Orange Widows Club

After their husbands died of an aggressive brain cancer, the widows of Vietnam veterans have found one another as they fight the VA for benefits. Read the story.

Long List of Agent Orange Decisions Awaits VA in 2017

The Department of Veterans Affairs must decide whether to add new diseases to its list of conditions presumed to be linked to Agent Orange. It also faces calls to compensate naval veterans and those who served along the Korean demilitarized zone. Read the story.

We posed the question to Dr. Ralph Erickson, the VA's chief consultant of post-deployment health services, who’s involved with the agency’s research efforts. Erickson, who’s had the job since last year, wouldn’t comment on the VA’s past reluctance to study these issues, saying only that his team is committed to it.

And if research someday proves a wartime exposure has harmed veterans’ children or grandchildren? Erickson, whose father served in Vietnam, said that’s a question that would have to be answered by VA lawyers. We pressed him for his personal view, and he too cited Lincoln’s words. But even then, he said it was a “hypothetical” and didn’t directly answer the question.

Vietnam vet Mike Ryan thinks he knows what the answer will be. Nearly four decades ago, his family was among the first to draw widespread attention to the possibility that Agent Orange had harmed veterans’ children. His daughter, Kerry, suffered from 22 birth defects, including spina bifida and other physical deformities.

After his wife died in 2003, he was left to care for his daughter until her death three years later at the age of 35. Lifting her out of bed several times a day to use the bathroom had damaged his back, leaving Ryan bedridden and alone. When we first reached the 71-year-old at his home in Boca Raton, Florida, he was reluctant to retell his tragic story.

“What’s the point?” he said. “The government won’t ever take responsibility.”

In the end, Ryan agreed to talk. Maybe sharing his story one more time would help others get the recognition his daughter never received.

If that happened, Ryan said he could die in peace.