On Friday, Feb. 8, a man wearing a military uniform motored up to a Malian army checkpoint in the ancient city of Gao, which had recently been liberated from Islamic militants that had held the arid country's expansive north since early 2012. The rider triggered an explosive belt, killing the bomber but merely wounding a Malian soldier standing nearby.

By the standards of suicide bombers, the Gao attack was unimpressive. But it was chilling nonetheless. It was the first suicide attack in the West African country since the beginning of the civil war last year, and an early blow in a nascent insurgency targeting Mali.

Last Friday's desultory blast was also a reminder of a recent military lesson. Speedy, high-tech, coalition-based military interventions, the kind increasingly favored by the U.S. after more than a decade of open-ended occupations in Iraq and Afghanistan, can begin neatly and end messily -- if they really end at all.

Washington's calculated support in Mali, including intelligence, drones, logistics and cash, enabled French, Malian and allied troops to quickly recapture northern territory from militant forces led by al-Qaida in the Islamic Maghreb, a.k.a. AQIM, the terrorist organization's North African affiliate. A coalition victory in the main assault was a foregone conclusion. It's the phase of the conflict after major combat that should worry U.S. officials. And that phase is beginning now.

Army Gen. Carter Ham, head of the U.S. Africa Command, put it best in mid-January during the early hours of the French-led campaign. Paris' bombers struck militant forces as French commandos mobilized Malian troops and armored battalions raced to reinforce France's African garrisons. Ham was apparently already thinking past the initial battles, to the possibility of a drawn-out insurgency. "The real question," Ham said, "is now what?"

Now more than ever, America wants neat, short conflicts. There's no appetite for drawn-out operations, to say nothing of large-scale troop deployments. But Mali is likely to underscore an unpleasant truth. Today's conflicts are usually anything but tidy or brief.

21st-Century Blitz

In March 2012, a coup by Mali's army toppled the elected government in the capital of Bamako in the south. In the resulting confusion AQIM fighters and other militants seized the less populated north. The fighting between the new Malian regime and the rebels quickly reached a stalemate.

The French Ministry of Defense began the planning and preparation for the current intervention way back last summer. Some French forces were already in Bamako. Others were on standby in nearby Chad, Senegal and Burkina Faso. Bertrand Clément-Bollée, head of French land forces, identified France-based troops that could be quickly sent to Africa to bolster the existing garrisons for a total deployment of some 4,000 troops. In October, Paris sent Harfang drones -- France's unarmed answer to America's Predator -- to begin tracking militant targets in the north. By late last year, the French intervention was primed.

In structure and purpose, the planned French assault force was indicative of an approach to warfare pioneered by the U.S. six years ago in Somalia, after Islamic militants captured most of that country. The U.S. was already bogged down in Iraq and Afghanistan. So in a secret meeting that summer, Jendayi Frazer, the top State Department official for Africa, told the Ethiopian president that the U.S. would support an invasion (.pdf) by Ethiopian forces. The attack came in December 2006, combining Ethiopian tanks and artillery with U.S. Predator drones, AC-130 gunships, carrier-based naval fighters and Special Operations Forces.

Within weeks the Islamists were on the run. As a proof of concept the "fantastic" "Somali job," as one foreign dignitary characterized it, was encouraging. But the second phase of that conflict was a reminder that invasions begin wars; they don't necessarily end them. After only a month's lull, Somali militants struck back against the Ethiopians with suicide bombers, roadside explosives and ambushes by fighters dressed as civilians. Fighting raged for years.

When militants in northern Mali attacked towards Bamako on Jan. 11, France's response followed the Somalia model. French armored vehicles sped north under intensive air cover. Special Operations Forces organized Malian battalions and led them into combat. The U.S. offered intel; sent transport and aerial refueling planes for support; and laid plans for a drone deployment to the region. In less than a month, French-led forces liberated all of the north's major cities, reportedly killing hundreds of militants at light cost to themselves. Paris is now planning to pull out its troops as early as March.

But if Mali continues to echo Somalia, the real nasty fighting is only beginning just as France plans to pull out its forces. The corrupt, undisciplined Malian troops and unproven West African peacekeepers who will remain behind might not be up to the task of defeating an entrenched insurgency. Suppressing Somali militants took another five years of painful effort after the invasion phase. Does Mali also face years of bloody irregular fighting before it can declare peace?

Indications are, yes.

Backlash

The French assault was a barely a week old when terrorists struck back elsewhere. Dozens of militants, reportedly including several Malians, seized a natural gas facility in Algeria along with hundreds of workers -- all in retaliation for the French-led intervention, the hijackers claimed. Twenty-nine militants and 37 hostages, three of them Americans, died when Algerian troops retook the facility.

The backlash in Algeria could be symptomatic of a new era of war, in which swift, high-tech military operations leave instability, insurgency and terrorism in their wakes. The difference between this era and the previous decade of battle is that the U.S. and its allies are no longer prepared to indefinitely deploy tens of thousands of troops to maintain security.

In a foreboding sign that "liberated" Mali might descend into insurgency, on Sunday militants traveling in canoes infiltrated Gao, earlier the site of the suicide bombing, and launched three separate attacks on French and Malian troops. "These attacks were quickly brought under control by Malian armed forces," the French defense ministry announced.

Abou Walid Sahraoui, a militant spokesman, rejected that assessment. "The combat will continue until victory, thanks to God's protection," he told Agence-France Presse. "The mujahedeen are in the city of Gao and will remain there."

Now what, indeed.