U.S. military documents reveal that in Afghanistan's most strategic districts, only about a quarter of the population supports the government in Kabul. The documents also include evidence that the government is riddled with corruption, that the Taliban-led insurgency is expanding in some areas and that violence has increased dramatically since 2009.

But those dire facts don't come from the mountain of the tens of thousands of mostly raw military reports released by the WikiLeaks organization. They come from an unclassified, public "progress report" on Afghanistan that the Pentagon delivered to Congress in April.

The most surprising thing about WikiLeaks' released trove of officially secret documents is how few surprises it contains.

That's largely because of a little-noticed, little-credited change in important parts of the U.S. military establishment over the last five years: a conscious decision to deploy the unconventional weapons of honesty and candor about the conduct of the war.

Mired in two wars that have been longer and more difficult than initially advertised, U.S. commanders have adopted an audacious but sensible strategy in describing facts on the ground: No more sugarcoating.

Why? Because one of the lessons of Vietnam was relearned in Iraq: When Americans believe they are being lied to about military operations, they stop supporting them.

In 2003, President George W. Bush and Defense Secretary Donald H. Rumsfeld portrayed Iraq as a quick and decisive triumph of American arms. When it turned out to be a long counterinsurgency for which the U.S. military was ill-prepared, public support collapsed.

The lesson some senior military officers learned was: Never overpromise. Far better to underpromise and, if possible, overdeliver.

That's why every major problem the WikiLeaks documents describe has already been revealed by U.S. officials, if not in such granular detail.

The revelation that U.S. officials believe elements in Pakistan's intelligence service support the Taliban? Officials have been making that charge for years. "The overall strategic approach of ISI needs to fundamentally change," Adm. Michael G. Mullen, chairman of the Joint Chiefs of Staff, said only the other day.

The revelation that NATO military operations often result in civilian casualties? "We've shot an amazing number of (civilian) people and killed a number and, to my knowledge, none has been proven to have been a real threat to the force," Army Gen. Stanley A. McChrystal, then the U.S. commander in Afghanistan, told his own troops at a public meeting in March.

The revelation that the U.S. military has deployed a secret commando unit to track down and kill Taliban leaders? The military command refuses to name the unit or talk about individual operations, but it has trumpeted its work as one of the unalloyed successes of the Afghan campaign.

The revelation that the Taliban might have access to shoulder-fired missiles that can bring down U.S. helicopters? An old story.

And if, as some have suggested, the real takeaway from the WikiLeaks' documents is that the war effort is in trouble, it's hard to accuse the U.S. military of conveying unwarranted optimism there either.

"We are not winning, which means we are losing," Mullen said last year.

"The going is likely to get harder before it gets easier," the new commander in Afghanistan, Army Gen. David H. Petraeus, said last month.

All that cold-shower candor helps explain why the WikiLeaks reports had no discernible effect on the House on Tuesday when it voted, 308 to 114, to approve $59 billion in additional funding for the war. Members of Congress who have paid attention already knew everything "revealed" in the WikiLeaks documents.

I'm not suggesting that the U.S. military or its civilian leaders in Washington now tell the unvarnished truth at every turn. When a military operation produces civilian casualties, they still often go into a defensive crouch. When the Marines took the southern Afghan town of Marja in March, they too-quickly declared it a famous victory (although when it turned out they were wrong, they admitted that too). They still haven't come clean on the inconvenient truth that U.S. military spending in Afghanistan is one of the chief causes of corruption there. And the spirit of candor is much stronger in the field than in the dangerous corridors of official Washington.

But most of the time, they have decided that honesty is the best policy, and they deserve some credit for that. The anticlimax of the WikiLeaks "revelations" is proof that the policy can work.

The big test for the new military candor won't be about the progress of the Kandahar campaign or civilian casualties. It won't even be about whether overall progress is being made.

The big test will come when President Obama asks his officers whether some version of success can be achieved at an acceptable price, in an acceptable time. Will Petraeus and the other authors of the military's new counterinsurgency doctrine be unsparing about the limits of their own creation?

That's when candor will count.

Doyle McManus is a columnist for the Los Angeles Times.