Afghan militiamen in the Achin district of Nangahar province, east of Kabul, on Dec. 27, 2015. (Mohammad Anwar Danishyar/AP)

At a ceremony inaugurating the new “Afghan Pentagon” here Monday, President Ashraf Ghani stressed the importance of building a modern military, subservient to the nation’s constitution and laws rather than to powerful individuals. He portrayed the gleaming new facility, built with U.S. funds, as the central command for that mission.

But 150 miles east, in the embattled district of Achin, news was spreading of an atrocity committed by a private pro-government militia over the weekend. After Islamic State forces captured and beheaded four of its members, Afghan officials reported, the militia retaliated by decapitating four Islamic State prisoners, later placing their heads on piles of stones along a main road.

The incident echoed the worst abuses of Afghanistan’s civil war two decades ago and raised fears that tribal strongmen, goaded by barbaric opponents, could undercut the Ghani government’s efforts to wage a professional fight against Taliban and Islamic State insurgents.

On Monday, Zahir Qadir, a tribal leader and deputy speaker of the Afghan senate, denied that the militiamen involved report to him. He has previously boasted that he has armed 200 men to fight “on the front lines” of the battle with Taliban and Islamic State forces in the province where the beheadings took place.

The retaliatory slayings and grisly display, first reported by Achin’s district governor and aired on Afghan media, aroused public horror and swift condemnation by human rights groups and others. There was shock that Afghan fighters had vengefully copied the tactics of their extremist adversaries and remonstration that the government had not done more to control private armed groups acting on its behalf.

“This behavior is unlawful and against humanity. We are not ISIS to do these things,” said Ahmed Ali, head of the provincial council in Nangahar province, which includes Achin. ISIS is another name for the Islamic State. “If militias are going to fight, they should be organized by the government and fight under its flag,” Ali said. “If they go out on their own, things like this can happen.”

The Washington Post traveled to the front lines of the fight against a Taliban resurgence in Afghanistan, the Marja district in Helmand province. (The Washington Post)

Ban on private militias

Ghani has ordered an investigation into the abuses and dispatched a delegation of officials to confer with local leaders. After taking office last year, he formally banned private militias, but critics and supporters said he faces a variety of obstacles in trying to carry out that policy, including political opposition by powerful former militia leaders and a need for extra police and foot soldiers as the insurgent conflict spreads.

“We strongly disagree with these atrocities, and the policy is clear — no one may create, finance or activate militias on their own,” said Gen. Dawlat Waziri, the senior spokesman for the Defense Ministry. “But Afghanistan has seen 35 years of war, and it makes things a bit complicated. It is up to the central government. If they let us, we will not have much difficulty stopping them.”

Like other ethnic clans, Qadir’s raised militias to fight in successive wars against the Soviets, rival Afghan strongmen and finally Taliban rulers. Qadir, once a supporter of Ghani, is now waging an open vendetta against him and has accused the president’s senior aides of supporting the Islamic State. On Monday, he announced that he had ordered his men to fire on any unidentified helicopters that land in Achin, where Afghan army forces have previously mounted operations.

No abuses comparable to Saturday’s beheadings have been committed by government forces in the year since NATO combat troops withdrew, leaving Afghans to fend off the persistent Taliban insurgency and the newer, more menacing threat of the Islamic State, which regularly uses beheadings as a terror tactic. In several cases, the tactic has been copied by the Taliban. The bulk of government fighting has been done by the national army, trained and equipped by the United States and other Western allies.

But the specter of civil-war-era atrocities, in which Afghan militia factions and commanders from all ethnic groups were implicated, is still fresh in the nation’s memory. The abuses, documented in reports by Afghan and international human rights groups, included rape and sexual mutilation, nailing victims’ heads, driving tanks over live bodies and suffocation in cargo containers.

Despite public demand, no official efforts were made to bring the responsible warlords to justice — they wielded enormous power, helped U.S. forces fight the Taliban and were veterans of the Cold War-era struggle against Soviet forces. Today, many of these former militia bosses hold high positions in government or public life, especially in the national legislature, and many still command the loyalty of sizable numbers of armed men.

“For various reasons, including international pressure, no one was held accountable or brought to justice, even at a time when it was possible, with 130,000 foreign troops here,” said Nader Nadery, a former official of the Afghan Independent Human Rights Commission, which conducted a detailed study of civil-war abuses. “Now the circumstances have changed, and it would be much harder to do.”

New security challenges

The Ghani administration took office last year with a reformist agenda that included forging a professional and cohesive security establishment. By the time NATO forces pulled out, Afghanistan had about 180,000 soldiers and 150,000 national police officers, as well as a small air force, but they have been stretched thin in the face of an aggressive and mobile enemy and have suffered from desertions, ethnic splits and poor coordination.

As a result, the government began to rely on, or at least tolerate, an assortment of revived or reconfigured local militias. Thousands of gunmen were mustered and briefly trained as special local police forces, but some acquired reputations for manhandling and extorting civilians. Others were paid by former commanders as personal guards but also became involved in fighting insurgents, including during the Taliban takeover of the northern city of Kunduz in October.

“Many of these commanders and militias have long-standing patterns of abuse, and reviving them now creates a real risk of more atrocities happening,” said Ahmad Shuja, associate researcher in Afghanistan for the New York-based group Human Rights Watch. “Ghani says he opposes them, but his actions have belied that. What happened in Achin is a potential war crime that must be investigated and prosecuted.”

But Ghani’s government faces a paralyzing quandary in trying to defang the country’s former militia bosses. Both he and his main opponent in the 2014 election, Abdullah Abdullah, courted various commanders. After the two men agreed to form a temporary “national unity” government, they brought in a few such strongmen, notably Abdurrashid Dostum as vice president. Others, left out of the spoils, have turned parliament into a bastion of opposition to virtually every policy Ghani proposes.

In recent months, some of the most powerful former warlords, rebuffed after proposing to join the anti-insurgent fight on their own terms, have formed a political alliance against Ghani’s government. The move has not involved violence, but experts say it could easily become an added source of danger for the country’s weak civilian rule.

“The beheadings in Achin could have dire consequences and create new hostility between the tribes, but what these militias did in the past is far worse. They killed, robbed and extorted. They buried people alive,” said Atiqullah Amarkhel, a retired army general and military analyst. “President Ghani says he is against them, but in practical terms he can’t do anything to stop them.”