How do successful counterinsurgencies evolve over time? Understanding the answer is paramount as the Obama administration tries to sort out the next steps on Afghanistan.

A rule of thumb is that even successful campaigns against insurgent groups typically take a decade or longer, as with the classic British campaign in Malaya after World War II or the U.S. effort in the Philippines a century ago or Brazil’s internal struggle half a century ago. For a more recent example, Colombia’s ups and downs of the last two decades in its fight against drug cartels and powerful insurgencies provide a useful guidepost.

A good deal of progress against the big cartels occurred in the 1990s, and after Alvaro Uribe Velez was elected president in 2002, the government had remarkable success in dealing with two insurgency movements, the FARC and ELN. Uribe stepped up attacks on insurgent forces and leaders, while the U.S. provided the helicopter support and precision munitions that the Colombian military units needed.

Fatality rates from violence declined by roughly half, as did the estimated size of the insurgencies (the FARC is thought to have fewer than 10,000 adherents now). The amount of territory held by insurgents declined substantially, and major cities became much safer.

Right-wing paramilitaries scaled back operations even more, and the country’s economy experienced healthy growth rates, averaging more than 4 percent annually over the last dozen years.

Violence Returns

Since 2010, however, when Uribe’s former defense minister, Juan Manuel Santos, became president, some degree of anxiety has crept back in. Santos has made strides in certain areas, partially defusing testy relations with neighboring Venezuela and Ecuador -- where insurgents still seek refuge -- and continuing Colombia’s impressive economic performance.

But there are signs that violence is on the gradual increase again. The insurgents have learned from their reverses, a regrouping that began in Uribe’s tenure, and adopted more effective tactics of shielding themselves from the government’s new methods of pursuit.

A few statistics, based on raw data from the Colombian police and presented at a recent Bogota conference by Alfredo Rangel of the University of Sergio Arboleda, highlight these growing worries. After declining to about a dozen incidents a year in 2007 and 2008, attacks on oil infrastructure jumped to 47 in 2011, similar to the level in 2004.

Guerrilla ambushes on Colombian security forces rose to 367 in 2011, almost identical to the 2002 tally, after having declined to about 150 annually five years ago. Kidnappings have increased modestly over the last two years, as well. The homicide rate is not increasing, but it has reached a plateau at almost 15,000 in a population of 45 million (by contrast, we view the higher level of 20,000 deaths a year in Mexico as a crisis, even though Mexico’s population is more than twice that of Colombia’s).

Santos’s new minister of defense, Juan Carlos Pinzon, is now making efforts to adapt. He is combining the military skills that Colombian forces already possess in spades -- for jungle and mountain warfare -- with the organizational changes and integrated counterinsurgency operations promoted by U.S. commanders such as David Petraeus and Stanley McChrystal in American-led missions in Iraq and Afghanistan. The hope is to reduce insurgent strength and activity by 50 percent in the 10 key areas of the country where they are now strongest, by the end of President Santos’s term in mid-2014.

Obama’s Obligation

It is too soon to say how successful Pinzon and Santos will be. The Obama administration needs to stay attuned to ways it can help. Congress finally approved a free-trade accord with Colombia last year, but so far, the administration’s policies toward Colombia in particular, and Latin America more generally, are not very path-breaking or concentrated. We can learn from the experience of the Clinton and Bush administrations, which among other things helped bring about and support the Plan Colombia aid initiative.

No huge new aid package is required. But even if additional forms of U.S. assistance and cooperation are limited in size and scale, they are hardly unimportant. They should include:

-- Providing greater technical reconnaissance support as Colombia seeks to track down insurgent leaders more efficiently.

-- Helping Colombia’s special forces better organize themselves.

-- Teaching skills to deployed soldiers and police in the field, as NATO has done in Afghanistan, where counterinsurgency advisory and assistance teams, known as CAAT, went on patrol with forces to train them in actual operations. Such education and cooperation can be a two-way street, as Colombia continues to have more expertise in areas such as jungle warfare than U.S. forces do.

-- Granting temporary aid increases to support development efforts for violence-prone parts of the country, such as a five-year road-construction plan.

A successful Colombia is important not only in its own right. It can also be a regional pillar for the U.S. -- a role that Colombia is already starting to play as Central American and even Mexican leaders seek its counsel on how to confront violent extremists. The U.S. can and should do more to help. We know from past success that our investments in Colombia are worth it.

(Michael O’Hanlon, a senior fellow at the Brookings Institution, is co-author, with Martin Indyk and Kenneth Lieberthal, of “Bending History: Barack Obama’s Foreign Policy.” The opinions expressed are his own.)

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To contact the writer of this article: Michael O’Hanlon at mohanlon@brookings.edu.

To contact the editor responsible for this article: Katy Roberts at kroberts29@bloomberg.net.