When Lt. Gen. David Petraeus returned from an inspection tour of Afghanistan in 2005 to brief then Secretary of Defense Donald Rumsfeld, he began with a simple image.

“The very first slide in the briefing that I gave to him was, ‘Afghanistan ≠ Iraq.’ And I then laid out to him the areas and issues in which you could compare and contrast the two countries and situations,” Petraeus recalled in an interview this month. “That comparison clearly established why, frankly, Afghanistan is a tougher nut to crack."

Events have vindicated his warning. As the seemingly intractable war stretches into its 18th year, military commanders who argue that any end is in sight are finding it a harder and harder sell.

Last month speaking to a gathering of civilian journalists who specialize in covering the U.S. military, Joint Chiefs Chairman Gen. Joseph Dunford conceded that “progress is too strong a word” to describe the movement toward a hoped-for reconciliation between the Taliban and the Afghan government.

Aside from a brief ceasefire in June, there have been no signs the Taliban are on the ropes, and all the trend lines indicate the war remains a stalemate. U.S. support has made the Afghan forces more effective than they were, but unable to stand up on their own.

“I understand those who are disheartened by this, but we never thought in the military this was going to be an easy job,” said Defense Secretary Jim Mattis when asked about the lack of progress at a forum sponsored by the U.S. Institute for Peace last month.

Mattis revealed that Afghan forces have been losing 15 soldiers a day, on average.

“Just look at the casualties, over 1,000 dead in August and September,” said Mattis, in making the point that the Afghan “lads” were on the front lines, not the 15,000 U.S. troops supporting them.

The latest report from the Pentagon’s internal watchdog concludes the Afghan National Defense and Security Forces “made minimal or no progress in pressuring the Taliban” in the most recent three month period, and “failed to gain greater control or influence over districts, population, and territory.”

The October 30 report by the Special Inspector General for Afghanistan Reconstruction also noted an uptick in deadly “insider” attacks, in which Afghan soldiers turn their weapons on U.S. and fellow Afghan troops.

The SIGAR report said 85 Afghans were killed and 36 wounded between January and August, and that didn’t include Army Maj. Brent Taylor, an American killed in a suspected insider attack this month, or the assassination of three prominent regional officials last month in an attack that wounded a U.S. one-star general, and missed the four-star commander of U.S. forces in Afghanistan, Gen. Scott Miller.

As Dunford was forced to admit, “Military pressure is what I would describe it as a necessary but not sufficient to achieve our strategic ends.”

The Iraq-Afghanistan divide Petraeus warned of became undeniable. Petraeus would go on to get his fourth star and command U.S. forces in Iraq. In 2006 he helped break the back of the al Qaeda insurgency by applying the lessons he distilled during a year of research in at the Ft. Leavenworth, namely protecting the population, securing territory block by block, and inspiring the so-called “Sunni awakening” that helped run the insurgents out of each town, one by one.

But unlike Iraq, Afghanistan is a poor country, with no history of a central government, no tradition of the rule of law, a very high rate of illiteracy, and a narco-economy based on exporting opium poppies.

Combined with the rough terrain and the fact that the terrorists have safe haven across the border in Pakistan, Afghanistan has earned its reputation as a the “graveyard of empires.”

Over the summer of 2017, President Trump was sold by his advisers on a new strategy designed to pressure the Taliban into accepting a peace deal. With no military solution, the U.S. is putting its hopes on the newly appointed envoy, veteran diplomat Zalmay Khalilzad to work his magic in wooing the Taliban into peace talks.

“Amb. Khalilzad is involved in obviously a lot of diplomatic work right now that we wouldn't talk about in public, so as not to disrupt it,” Dunford said.

Mattis called Khalilzad “a force of nature,” and said he is “hard at work” on an Afghan-led, Afghan-owned peace and reconciliation effort.

“This is the approach we're trying to sustain right now. It is working from our perspective,” Mattis said, “but it is heartbreakingly difficult to accept that the progress and violence can be going on at the same time.”

But Petraeus, who commanded U.S. and NATO forces in Afghanistan in 2010 and 2011, argues the singular pursuit of reconciliation may be misguided, obscuring the larger objective.

“I think it is very important to keep in mind why we went to Afghanistan and the reason why we have stayed,” says Petraeus. “We went to Afghanistan to eliminate the sanctuary in which the 9/11 attacks were planned, and we have stayed to ensure that that sanctuary cannot be reestablished by al Qaeda or, now, by the Islamic State or other extremist groups, and also to ensure we have a platform for our regional counterterrorism campaign.”

Reconciliation, argues Petraeus, is “a legitimate aspiration, something we should certainly seek to achieve, however slim the prospects might be,” but the U.S. should be prepared to stay in Afghanistan indefinitely, even if the Trump strategy to end the war fails.

“Look, we have had tens of thousands of troops in Korea for approaching 70 years. We’ve had them even longer, in larger numbers, in Europe,” says Petraeus. “If you can get the cost down in blood and treasure, I think this is a sustainable commitment, and I believe it should be sustained given the importance of the mission.”

So far this year eight American troops have been killed in action in Afghanistan, three from insider attacks. The Pentagon does not release the number of U.S. wounded.

The current U.S. Afghanistan commander Gen. Miller is making adjustment in procedures to try to mitigate the risk of so called “green-on-blue” attacks, inspired by the Taliban, but he too has testified to Congress that there is no military solution.

“Frankly, you are not going to get reconciliation until it is clear to the insurgent groups that we do have the will to stay in the shadow of the Hindu Kush and to continue to achieve the mission that took us there in the first place,” Petraeus argues.

“Should you try to pursue local reintegration where you can? Certainly,” he says. “But if you think you are going to take a certain hill, plant the flag and go home to a victory parade, you’re sorely mistaken.”

