—The Iraq wars and Afghanistan
So far, the wars in Iraq, Afghanistan and the first Persian Gulf conflict in the early 1990s are costing about $12 billion a year to compensate those who have left military service or family members of those who have died.
Those post-service compensation costs have totaled more than $50 billion since 2003, not including expenses of medical care and other benefits provided to veterans, and are poised to grow for many years to come.
The new veterans are filing for disabilities at historic rates, with about 45 percent of those from Iraq and Afghanistan seeking compensation for injuries. Many are seeking compensation for a variety of ailments at once.
Experts see a variety of factors driving that surge, including a bad economy that's led more jobless veterans to seek the financial benefits they've earned, troops who survive wounds of war and more awareness about head trauma and mental health.
It's been 40 years since the U.S. ended its involvement in the Vietnam War, and yet payments for the conflict are still rising.
Now above $22 billion annually, Vietnam compensation costs are roughly twice the size of the FBI's annual budget. And while many disabled Vietnam vets have been compensated for post-traumatic stress disorder, hearing loss or general wounds, other ailments are positioning the war to have large costs even after veterans die.
Based on an uncertain link to the defoliant Agent Orange that was used in Vietnam, federal officials approved diabetes a decade ago as an ailment that qualifies for cash compensation — and it is now the most compensated ailment for Vietnam vets.
The VA also recently included heart disease among the Vietnam medical issues that qualify, and the agency is seeing thousands of new claims for that issue. Simpson said he has a lot of concerns about the government agreeing to automatically compensate for those diseases.