When President Obama surged 30,000 additional U.S. troops into Afghanistan in 2010, the new forces were concentrated overwhelmingly on two volatile areas of southern Afghanistan: Helmand and Kandahar Provinces. Now, as the troop surge is practically over, those provinces still rank as the most violent in the entire country.

According to Marine Gen. John Allen, the commander of the war, ten districts around Afghanistan account for fully half of the insurgent violence in the country. (Afghanistan has 405 districts.) According to a breakdown provided to Danger Room by the Pentagon, six of those districts – Sangin, Now Zad, Nad Ali, Kajaki, Musa Qalah, and Nahr-e Saraj – are in Helmand Province, where the Marines started fighting a costly and grueling battle with the Taliban in 2009. Three more of them – Maiwand, Panjwei and Zharay – are in Kandahar, the Taliban's birthplace and the scene of similarly arduous Army fighting from 2010 to the present. (The final district, Pul-e Alam, is in the eastern Logar Province.)

Spokespeople for the International Security Assistance Force (ISAF), NATO's military command in Afghanistan, did not immediately respond to inquiries seeking elaboration. But there are around 80,000 U.S. troops remaining in Afghanistan, and the remaining 10,000 surge troops are due to leave the country by the end of September. The persistence of the violence in the provinces they bled and died to pacify raises questions about the durability of what the U.S. will leave behind in Afghanistan.

The Marine Corps, for reasons that remain obscure, decided in 2009 to focus its fight on sparsely-populated Helmand Province. They've fought hard and recently in Sangin and Kajaki; and in July 2011, ISAF boasted to Danger Room that violence in Nad Ali was down 70 percent from the previous year. With the surge forces receding, the Marines now find themselves spread thin: Marines have only a single company for each of the districts of Now Zad and Musa Qaleh.

Rajiv Chandrasekaran, a Washington Post associate editor, focused much of his recent book about the war, Little America, on the Marine fight for Helmand. While he noted that several of the violent districts aren't ones where the Marines donated the majority of their focus in the province – some are the responsibility of British forces – the overrepresentation of Helmand in Afghanistan's most violent districts "raises some fundamental questions about the Marine narrative that they fundamentally transformed Helmand province," Chandrasekaran said, particularly Now Zad, Musa Qaleh and Sangin, places where the Marines have claimed major progress. "If six of the ten most violent districts in the country are still in Helmand, it does call into question the sustainability of some of their gains."

Kandahar, on the other hand, is one of Afghanistan's most populous regions – not to mention the traditional home of the Taliban. And there ISAF has some good news to report: the United Nations found that civilian casualties declined in 2012, although they remain triple the rate of civilian deaths in 2008. Kandahar City, the site of intense fighting in 2010 and 2011, is no longer one of the hottest of hot spots. Neither is the adjoining Argandab River Valley, where U.S. troops flattened entire villages that the Taliban boobytrapped.

But coalition forces fought hard in Kandahar's Maiwand and Panjwei provinces – where the fight grew so frustrating and American leadership became so weak that a band of rogue, sadistic soldiers formed a "Kill Team" to take revenge. One Army veteran of Iraq and Afghanistan who recently ended a year's tour in Kandahar described it as the most arduous thing he has ever done in his life.

Nonetheless, after two years of combat in Kandahar and Helmand, those provinces still account for an outsize proportion of Afghan insurgent violence.

Nor is violence is down significantly in Afghanistan as a whole. Allen, speaking to Pentagon reporters on Thursday, said the overall insurgent violence in the country has dipped three percent from this time last year – a figure he conceded "may not be statistically significant." The previous year, ISAF said that insurgent attacks remained basically level with summer 2010 levels – when the full complement of surge troops arrived in Afghanistan. The purpose of the surge was to reverse the momentum of the Taliban in order to hand over a stable Afghanistan to the Afghan government. If measured by the rate of insurgent activity, the surge at most dented the Taliban's momentum.Allen doesn't see it that way. He contended to Pentagon reporters that U.S., Afghan and allied troops pushed the Taliban out of former redoubts and essentially forced them into small clusters. He cited the ten districts accounting for half of the violence in the country as a positive indicator.

It is doubtful that the post-surge U.S. presence in Afghanistan will take those ten violent districts head-on. By the fall, the Marine presence in Helmand will fall by 10,000, leaving 7,000 Marines in the province. After the summer, the likely focus of the Army-led task forces in Kandahar will be on consolidating security gains and mentoring Afghan troops to prepare to secure the future. That future, Allen told reporters, will not be an peaceful one: after NATO ends its combat mission in 2014, Afghan forces must continue to "deal with violence."