At a rare congressional hearing Tuesday morning about how to spend less -- not more -- on defense, panelists raised a question that has barely ever been asked on Capitol Hill.
Namely: What lesson have we learned from the wars in Iraq and Afghanistan? Is it that we should prepare for similar conflicts in the future, or that we should avoid them like the plague?
Over the past nine years, it's gradually become accepted that our military's duties include not just deterrence and conventional warfare but counterinsurgency, nation-building, counterterrorism and propping up fragile governments.
A recent Congressional Research Service report determined that the more than $1 trillion that's been spent on Afghanistan and Iraq make the "war on terror" the second most expensive U.S. military action, in constant dollars, after World War II.
So when it comes to making substantial cuts in the country's enormously expanded military budget, said Gordon Adams, a professor of international relations at American University, "the key is going to be in mission discipline."
"We are at a point in American history where a serious, baseline discussion of strategy and mission is essential," Adams told a House oversight subcommittee for national security and foreign affairs.
Congress needs to do a "hard scrub" when it comes to what missions it considers appropriate for the armed forces going forward, he said. "Which ones are most important to the security of the U.S.?" Is the chief takeaway from Afghanistan and Iraq "that our national security is engaged every time there is a terrorist attack, every time there is a insurgency," and so on?
Carl Conetta, co-director of the Project on Defense Alternatives, noted that defense spending is now at levels significantly above the peaks of the Cold War, and is up 96 percent in constant dollars since 1998.
"We need to look at this budget with new eyes," he said.
"The fabulous cost, slow progress, and uncertain outcome of recent efforts at regime change, armed nation-building, and large-scale counter-insurgency make them a poor strategic choice, when other approaches are available for fighting terrorism and countering proliferation," Connetta said in his written testimony.
Even among supporters of the wars, "few seem eager to repeat the exercise elsewhere in the future," he wrote. "Can we draw a broader lesson from this?"
Benjamin Friedman, a research fellow at the libertarian Cato Institute, insisted that "a more restrained defense strategy would not only save money, it would improve our national security."
"Defining security so broadly is actually counterproductive," he said.
The call for a broader debate was popular up on the dais -- at least on the Democratic side.
"We need a thoughtful, non-rancorous discussion about the appropriate mission," said Rep. Barney Frank (D-Mass.).
Frank has been actively promoting ideas to cut the defense budget. In April, he put together a group of scholars to look specifically for defense cuts, unlike President Obama's deficit-reduction commission, which appears to be focusing elsewhere. The group issued its report last month, outlining nearly $1 trillion in defense budget cuts over the next 10 years.
"What should we be doing? What policy should we be setting? We have not had that conversation," Frank said Tuesday.
"I don't know that we really have a defense budget," said Rep. John Tierney (D-Mass.) who chaired the hearing. "It seems to me that we just spend whatever we want to spend."
Tierney said he hopes there will not be another war like Afghanistan or Iraq in the nation's future. "What's our interest there? I don't think we ask that question enough," he said.
Rep. Peter Welch (D-Vt.) welcomed the idea of a serious examination of the armed forces' structure and mission. "That's a debate Congress has not yet had," he said.
Rep. Stephen F. Lynch (D-Mass.) called for a review of the "amazing" amount of inherently governmental functions and responsibilities that have been outsourced to contractors. "These contractors are cleaning up and they're making pretty hefty profits, and that's all at the expense of the American taxpayer," he said.
Most Republican members of the subcommittee did not share the Democrats' concerns about mission and money.
"Defense is where we're supposed to spend tax dollars," said Rep. Jim Jordan (R-Ohio), who indicated his support for reductions in "everything else."
Rep. Blaine Luetkemeyer (R-Mo.) warned: "We can be penny wise and security foolish."
[Correction: An earlier version of this story indicated that the panel's Republicans were unanimous in their opinion. But Rep. John Duncan (R-Tenn.), spoke out against current levels of Pentagon spending on the grounds that "most of, or at least very much of what the Defense Department does right now is just pure nation-building.. and we simply can't afford it."]
Dan Froomkin is senior Washington correspondent for the Huffington Post. You can send him an e-mail, bookmark his page; subscribe to RSS feed, follow him on Twitter, friend him on Facebook, and/or become a fan and get e-mail alerts when he writes.