The price tag for the wars in Afghanistan and Iraq were staggering – somewhere in the neighborhood of $2.2 trillion.

But we should not forget that those wars were fought with borrowed money. That means the long-term costs could prove to be far, far greater than even the initial price. How much? According to Reason’s Eric Boehm, $6 trillion, or more:

“The costs of these wars continue long after we withdraw, since they are debt-financed and we will be paying interest on that debt for years—even decades—to come,” Heidi Peltier, project director for the Costs of War Project at Boston University, tells Reason.

Peltier’s research shows that the interest costs of the post-9/11 wars in Afghanistan and Iraq had already topped $1 trillion. By the end of the current decade, interest on the war debt will likely exceed the final official tally of the wars’ cost. And the final price tag for those operations could eventually exceed $6 trillion—with American taxpayers still paying the tab when the 50th anniversary of 9/11 arrives.

That’s just the cost to fight. As for the cost in lives lost and forever changed:

An accurate accounting of the war in Afghanistan must take into account the roughly 2,400 American service members, 3,800 American contractors, 66,000 Afghan security forces, 47,000 Afghan civilians, and others (including journalists and aid workers) who were killed. In all, the Costs of War Project estimates that at least 238,000 people died as a result of the war in Afghanistan.

There will also be ongoing costs to cover the medical treatment for the four million veterans of the two post-9/11 wars, many of whom are injured or disabled. Those obligations will eventually total $2 trillion, according to an estimate from Linda Bilmes, a researcher at Harvard University’s Kennedy School and a longtime critic of the official estimates of the wars’ cost.

“Uncle Sam has spent more keeping the Taliban at bay than the net worths of Jeff Bezos, Elon Musk, Bill Gates, and the 30 richest billionaires in America, combined,” notes Forbes’ Christopher Helman and Hank Tucker.

We spent it all, blood and treasure, plus debt, and loss…only to see the Taliban return.