At 9 a.m. on Monday, Nov. 20, one of the few tanks belonging to the M23 rebels of eastern Congo fired a single shell into the international airport on the outskirts of Goma, the second biggest city in the Democratic Republic of Congo (DRC).

The townspeople, who looked up to see the first of 1,000 or so guerrillas marching on the city, began walking and running toward the city center, carrying their children and anything else they could. After a short while they were overtaken — by two large trucks packed with foreign soldiers from the U.N. peacekeeping force for Congo, Monusco.

Mandated to protect Congo’s civilians, with 19,000 men in uniform and costing $1.4 billion a year, the world’s biggest and most expensive peacekeeping operation was literally leaving its charges in its dust. Later in the day Monusco, far better armed and more numerous than the rebels, simply stood and watched as the M23 — easterners who oppose the central government in Kinshasa — took Goma almost without firing a shot. France called Monusco’s conduct "absurd.”

The Congolese were less forgiving. Across the east of the country, angry mobs surrounded U.N. positions, threw stones at aid workers and burned U.N. compounds. Asked what they thought of Monusco, a group of young men standing by the shore of Lake Kivu in Goma cried out in unison: "Useless.” Amani Muchumu, 18, had a message for the peacekeepers. "You could not defend us,” he declared. "You are dismissed.”Monusco’s dismal performance this past week caps a wretched 12 years for the force that, by dint of its size and costliness, was meant to fly the flag for all 16 U.N. peacekeeping operations around the world.

Since it was set up in November 1999, the then MONUC (renamed Monusco in 2010) has proved extraordinarily inept. Rarely has it engaged the various militias that hold eastern Congo in their murderous sway. Just as awkwardly, bound by the terms of its deployment to support the national government, it has found itself backing not just one of the most corrupt states in the world but also a Congolese army whose generals are among the most industrious of Congo’s thieves and whose rank-and-file boast one of the worst records on human rights, and cowardice, in eastern Congo.Perhaps worse even than failing to keep or establish peace, Monusco has also failed spectacularly in its most fundamental mission: protecting civilians. In 2005, MONUC expelled 63 of its soldiers for paying refugee children for sex. A separate internal inquiry the same year found that Pakistani peacekeepers sold weapons to militias in exchange for gold.

While those incidents may be exceptional, TIME has seen in repeated trips to eastern Congo how, at the first sign of trouble, blue-helmet peacekeepers habitually barricade themselves into their bases, leaving crowds of several thousand refugees who tend to gather outside to fend for themselves.Now TIME has learned from two NGO sources in eastern Congo about an incident that memorably illustrates Monusco’s callous ineffectiveness. In September the town of Pinga, west of Goma, was taken over by a private militia and protection racket called Mai Mai Cheka (after its commander Colonel Cheka).

Cheka, wanting to force the peacekeepers out of town but unable to persuade them to leave their base, resorted to the kind of barbarism he thought no U.N. force could ignore. On his orders, two civilians from the town were abducted, decapitated and their heads thrown at the base gates, while Cheka shouted: "Come out!” "Do you think Monusco ventured out of the gate?” asks a senior aid worker with knowledge of the incident. "[They did] nothing.

How safe did the population feel after that?” Other humanitarian workers fear a true catastrophe may now be unfolding nearby as a result of Monusco’s weakness. In the town of Masisi, another militia, Raia Mutomboki — originally a self-defense group that now pursues an aggressive campaign of ethnic cleansing against Rwandese — is now attacking the civilian population for the third time this year with the apparent aim of eliminating thousands of ethnic Rwandese from the area. Though Monusco has a base in the area, it has failed to intervene. (Monusco failed to respond to repeated attempts to contact it for this article.)With that kind of record in Congo, now topped by last week’s shameful conduct, many are asking whether the whole idea of peacekeeping needs rethinking or even scrapping completely, at least as it is currently conceived at the U.N. Among the most confused by what they are meant to be doing, it seems, is Monusco itself. A staffer in Goma told TIME that Monusco was still robotically patrolling the town as if nothing had happened "because that is our mandate. We support the [Congolese army] to fight M23, but it’s not up to us to fight directly with the M23.” The staffer added that Monusco currently felt unable to fight without the Congolese army, seeming to forget that the founding justification for foreign humanitarian intervention is when national forces on the ground are unwilling or unable to take care of their own. Asked whether Monusco was secure in the face of popular anger, the official replied without any apparent irony: "Any misconduct will be met with punishment by the rebels.” A humanitarian official at an international aid group in Goma says Monusco’s behavior has graduated from incompetent to dangerous. "They’re telling lies,” he says. "We’re told that Monusco is aerial bombing M23 positions, then a few hours later the M23 is in Goma.” Caelin Briggs, an advocate at Refugees International, says: "The current system is, quite simply, not working. Pretending that it is only serves to make the problem worse.” About the only people who approve of Monusco, it seems, are the rebels themselves. "We don’t have a problem with Monusco,” says Lieutenant Vianney Kazarama, M23 spokesman, at a lakeside hotel in Goma. "They’re following their mandate, doing their job and doing it well. We’d be happy to collaborate with Monusco.”For some, Monusco’s ineffectiveness opens up some big questions about all foreign intervention. Congo abounds with examples of how foreign assistance, though well intentioned, can sometimes turn out to be nothing of the kind. The 1994 influx of hundreds of thousands of génocidaires from Rwanda — the Interahamwe — provided the spark for the near constant war that has raged ever since. That fledgling flame was nursed, however unintentionally, by the international community: while the Interahamwe had been defeated by the forces of the Rwanda Patriotic Army, over the border in Congo a giant humanitarian aid camp operation gave the génocidaires the space and opportunity they needed to regroup, rearm and refinance. More recently, the Dodd-Frank Act of 2010, which contained a clause mandating U.S. companies to disclose whether they use minerals from Congo, has often had the opposite effect to that intended. Rather than clean up the trade, U.S. companies simply stopped using Congolese minerals, leaving mines in Congo dependent on the illegal trade.Monusco’s Goma fiasco is merely the most recent example of the international community’s questionable record in eastern Congo. It’s also only the latest spur to efforts by neighboring Rwanda and Uganda to take back control of their region’s own affairs. This year, leaders of the 11-nation International Conference on the Great Lakes agreed to set up their own regional stabilisation force designed to eventually replace Monusco in eastern Congo. And on Wednesday at a meeting in the Ugandan capital, Kampala, Rwanda’s President Kagame, Uganda’s President Yoweri Museveni and Congo’s President Joseph Kabila issued what their advisers described as a "breakthrough” statement on the "deteriorating security and humanitarian situation” after Goma’s fall to the rebels. Kagame and Museveni "made it clear that even if there were legitimate grievances by the mutinying group known as the M23, they cannot accept expansion of this war or entertain the idea of overthrowing the legitimate government of the DRC or undermining its authority. Therefore, the M23 rebel group must immediately stop its offensive and pull out of Goma.” For his part, Kabila "made a commitment to look expeditiously into the causes of discontent and address them.” All three also agreed to draw up "a comprehensive and operational plan geared towards lasting peace and stability … as a matter of urgency.”All of which you might expect to be welcomed by the international community. In fact, those initiatives were met with stony silence. That is due to the dominant opinion inside the U.N., the aid community and Western media that the leaders of Rwanda and Uganda are not well intentioned pursuers of peace. Rather, they are seen as the cause of much of the instability through their alleged backing of the M23 and other militias. The strategy in Kigali and Kampala, say their accusers, is to create chaos, then be called in to make peace, a nefarious plan born of a desire to both improve regional security and establish an economic dominance over eastern Congo’s considerable mineral and metal resources, such as gold, diamonds and coltan. Two groups, Human Rights Watch and the U.N. Group of Experts (GOE) on Congo, have collected substantial circumstantial evidence in support of foreign backing for the M23, and it was perhaps no coincidence that as Kagame, Museveni and Kabila met in Kampala, a GOE report once again accusing Rwanda and Uganda of backing the M23 was being leaked in New York City.Rwanda provides "direct military support, facilitation of recruitment, encouragement and facilitation of [Congolese army] desertions, as well as the provision of arms and ammunition, intelligence and political advice,” said the GOE. Meanwhile, Uganda gives the M23 "direct troop reinforcements … weapons deliveries, technical assistance, joint planning, political advice and facilitation of external relations.”Kigali and Kampala both regularly deny the changes and point out that the U.N. and the aid groups — with tax-free salaries of up to $200,000, and a $75,000 car and $5,000-a-month in rent thrown in — are hardly disinterested parties to the conflict themselves. At its most fundamental level, this is a dispute about sovereignty and whether, in a 21st century multipolar world, bossy Westerners still get to tell Africans what to do. In other African trouble spots such as Mali and Somalia, foreigners are only too happy for Africans to take the lead, and pay the human cost, even if the outside world foots the financial one. In Somalia, another place where U.N. peacekeeping was a failure, that approach has proved a success: AMISOM is steadily taking territory from the Islamist militants of al-Shabab.The crucial difference between an African intervention force and a U.N. one, it seems — and one that is not only a riposte to Rwanda and Uganda’s accusers but, ultimately, to the whole idea of neutral foreign intervention — is that with nothing personal at stake, the U.N. is often unwilling to do what it takes to win. More than 1,000 Ugandan soldiers have been killed in Somalia since 2007 as part of AMISOM. Since 2000, the far larger MONUC-Monusco have suffered just 47 casualties. In Congo, a Uruguayan platoon officer explains: "I have to make the right decision for everyone concerned. I have a wife and a son back home. My men have families too. I want us to get out there, but it’s not safe.” For the people of Goma, that’s a level of commitment now forever encapsulated by a dusty view of the rear of a fleeing U.N. troop truck.