As defense budget wranglings continue on Capitol Hill, much of the debate about one of the Pentagon’s largest expenses – Afghanistan – centers around just how effective the decade-long fight has been. Put more sharply, what has America received for the $443 billion it has spent so far on the war? (That's the latest estimate from the Congressional Budget Office covering 2001-2011.)

At the Pentagon and in testimony on Capitol Hill, the US military is taking part in its own cost-benefit analysis. Here are three top lessons the US military has learned in Afghanistan.

1. Watch the money

Staggering corruption has consistently undermined the mission of US troops in Afghanistan, according to top US officials.

A new congressionally mandated report on Afghanistan released in late July paints a dismal picture of the scale: It finds that “a significant proportion” of the $400 million the US has invested in large-scale projects in 2011 has been “wasted, due to weaknesses in planning, coordination, and execution, raising sustainability concerns and risking adverse counterinsurgency effects.”

These are projects designed to win local support in areas where US troops are fighting.

Yet the money continues to flow. Already, the US has committed more than $90 billion in development dollars in 2013 – a tough sell for voters in a time of fiscal austerity, noted Sen. Robert Menendez (D) of New Jersey during a Senate Foreign Relations Committee hearing Tuesday.

“How do we justify and expect that we will effectively – if we were to commit to those funds – effectively use those funds toward the development of a sustainable economy in Afghanistan, something that I could go to taxpayers back in New Jersey and say, ‘Yeah, this is worthy of our support and it's going to be well spent based upon experience we've had so far?’ ” he said during the hearing.

It doesn’t help that the Afghan finance minister has come under investigation, after an Afghan television network turned up what may be payoffs from businesses deposited into his private bank accounts.

This does not serve to increase confidence among the Afghan citizenry ahead of 2014 elections, also the year US combat troops are set to leave the country.

“Ultimately, it is the political transition that will determine whether our military gains are sustainable, and the strength and quality of the Afghan state we leave behind,” noted Sen. John Kerry (D) of Massachusetts, who chairs the Senate Foreign Relations Committee. Yet corruption and graft make it difficult for both American voters and their Afghan counterparts to have any confidence in the political process.

2. Make it last: Build an Army Afghanistan can sustain after US troops leave

It has been a cornerstone of US military policy in Afghanistan: As Afghan soldiers and police stand up, US troops can stand down.

That has been happening more slowly than US officials had hoped, with an attrition rate of some 25 percent per year within the Afghan National Army (ANA), according to a seniorNATO official.

Brig. Gen. Thomas Putt, director of Afghan National Security Forces Development in Kabul, promised that NATO will meet its goals to build up the size of Afghan security forces to suitable levels by October.

Many new recruits have been attracted to the force by literacy programs sponsored by the US military. Most Afghans are illiterate, and teaching new recruits how to read “has become a real draw for the security forces as we move forward,” Putt said during a Pentagon briefing Aug. 1. “It is also, I think, a secret weapon that the insurgents can’t provide, and that’s one draw down the road that we think will pay huge dividends as we go forward.”

But the ongoing question will be how to sustain these forces long after US troops leave.

So far, very few Afghan units can operate “independently” of US advisers. This fact was brought into sharp relief with a Government Accountability Office (GAO) report released in July that charged the Pentagon with being evasive when it comes to evaluating the capabilities of Afghan security forces. It found that the “tools used to assess the performance of the [Afghan military] units have changed several times.”

Indeed, the highest level of achievement for an ANA unit had previously been “independent.” As of August 2011, that top rating was changed to “independent with advisers.” The Pentagon made these changes, the GAO charged, to make it seem as if the ANA were making more progress than it actually has. The GAO investigation further found that these changes were "partly responsible for the increase in ANSF units rated at the highest level."

Much of the costs for standing up and even maintaining the Afghan Army will require US money for years to come. The United States is covering most of the costs of the ANA and, with an annual budget of $4.1 billion, “the Afghan government has limited ability to financially support its security forces,” the GAO reports.

The looming threat is that after US troops leave, ANA fighters might have to take their US-provided training and find work elsewhere if they want a steady paycheck. This, in turn, raises the specter of private militias.

The nominee to be the next US ambassador to Afghanistan, James Cunningham, addressed the threat in testimony before the House Armed Services Committee on July 31. “I think the talk of rearming and of reforming of militias is overstated,” he said. “But the temptation is there, and the uncertainty about how various groups will advance their interests in the future is very much on the table.”

3. Pay attention to the neighbors

The US relationship with Pakistan, which shared a border with Afghanistan, has been an ongoing source of frustration for the US military.

It was only in June that Pakistan reopened its border after closing it in November 2011, when American forces accidentally killed 24 Pakistani soldiers during an airstrike.

This was previously the crossing point for the vast majority of the Pentagon’s supplies for its troops in Afghanistan. Pakistani officials said they were waiting for the US to apologize for the deaths.

That this apology was long in coming speaks to the resentment that some Pentagon officials harbor for what they see as Pakistan's failure to earnestly crack down on Taliban insurgents that continue to launch crossborder attacks on US troops.

Pakistani officials have resentments of their own – specifically, US drone strikes targeting Al Qaeda militants hiding out in Pakistan's tribal regions, which in some cases have also killed Pakistani civilians.

American lawmakers for their part see a great deal of US aid to Pakistan expended without much US strategic gain. Sen. Bob Corker (R) of Tennessee described US-Pakistan ties as a "pay-for-play" relationship as he inquired about US strategy during a Senate Foreign Relations Committeehearing. "Since it is more of a transactional relationship – not one that is built on goodwill – how do we leverage the resources that we have to cause Pakistan to act in ways that we would like to see them act?"

This is the ongoing question within the halls of the Pentagon, as well as on Capitol Hill. “What happens in the region ... as a whole will do more to determine the outcome in Afghanistan than any shift in [US] strategy,” Senator Kerry noted in the same hearing. “And Pakistan, in particular, remains central to that effort.”