* Colombia focuses on rebel financial, logistics units
* Government plans at least 12 dedicated task forces
By Luis Jaime Acosta and Jack Kimball
BOGOTA, Feb 17 (Reuters) - Colombia is redesigning its fight against Marxist guerrillas, making the destruction of key rebel military and financial units as much of a goal as killing their leaders, sources familiar with the plan say.
Helped by billions of dollars in U.S. aid during the last decade, Colombia's armed forces have used better intelligence and mobility to batter guerrilla armies, pushing their fighters into ever more remote hideouts.
The largest group, the Revolutionary Armed Forces of Colombia, or FARC, has adjusted its tactics, however, by returning to its guerrilla roots and using smaller units - in contrast to the 1990s when it seized swathes of territory.
So while the army has killed top FARC commanders such as Raul Reyes in 2008, Mono Jojoy in 2010 and Alfonso Cano in 2011, the war goes on.
Military and civilian sources familiar with the new strategy say the main change is to increase the focus on the FARC's logistics and financial operations, as well as its main fighting units.
"The strategic center of gravity for the FARC isn't their leaders, it's their structures," a local military source said.
"Mono Jojoy died and nothing happened, the FARC continued. Cano died and nothing happened either. There was demoralization and a weakening, but the rebels aren't finished."
The new task forces will aim to destroy key rebel "fronts", which are similar to battalions and combine to make up bigger regional "blocks" resembling army divisions. Some blocks are led by leaders from the FARC's ruling seven-member secretariat.
The revamped strategy is to dismantle the fronts involved in cocaine smuggling, arms trafficking, the manufacture of bombs and illegal mineral mining, as well as specialist combat units such as the feared Teofilo Forero mobile front, the sources said.
EARLY VICTORY FOR 'OMEGA'
Colombia has activated a total of seven task forces, and plans to add at least five more. Made up mostly of personnel from army units, they operate autonomously and are under the direct control of the head of the armed forces.
The largest of the task forces so far is "Omega", which has around 25,000 men with air, artillery and marine support.
In an apparent early victory, the military said it was Omega troops who killed the head of the FARC's "62nd front" in the oil-producing Meta province this week. He was not part of the FARC's secretariat, but had been a vital coordinator between its southern and eastern blocks.
When Alvaro Uribe took office as president in 2002, the FARC was at its strongest since it took up arms in the 1960s.
It had as many as 17,000 fighters and posed a serious threat to the state. Hundreds of rebels at a time launched brazen attacks on military bases, the FARC controlled large swathes of territory and took people hostage from cars on major highways.
Helped by U.S. funding, training and intelligence support, Uribe and his successor, President Juan Manuel Santos, have since halved the FARC's fighting force to about 8,000 rebels.
Experts say the number of FARC attacks has increased since 2008, but that overall they have had less impact - the rebels are relying more on landmines and on hit-and-run strikes in a trend that began during Uribe's presidency and has continued.
Security is vastly better than a decade ago and that has helped attract record levels of investment, mainly in oil and mining. Colombia expects to see foreign investment of $16 billion this year, compared with about $2.1 billion in 2002.
The military's new strategy will focus mainly on the FARC, but also on the smaller ELN insurgent group and on new criminal gangs that include former drug-smuggling groups and right-wing paramilitaries who laid down their weapons in 2003-2006.
PETRAEUS BRIEFED ON PLAN
The task forces will be deployed in some of Colombia's most violent provinces, where heavy combat regularly breaks out. One area, Cauca, has been dubbed "Cauca-kistan" by local troops.
Colombia briefed CIA director David Petraeus - a retired U.S. general who ran the wars in Iraq and Afghanistan and oversaw the development of the U.S. military's counter-insurgency manual - during his visit to the country last month.
"It was almost all that was talked about," one source said.
Many of the conflicts in Colombia are fights over drug routes and cocaine production. In some regions, rebels have alliances with criminal gangs, while in others they battle them for control of a share in the multi-billion-dollar industry .
Asked about the revamped plan, Defence Minister Juan Carlos Pinzon would not comment on the specific details.
"We've been carrying out a complete strategic revision that gives us new alternatives and new abilities to fight all illegal groups, whether they be the FARC, criminal gangs, or the ELN," Pinzon said. "We are constantly in a process of innovation."
The FARC is Latin America's longest-running insurgency and has survived various tactics by different government since its birth in 1964. It was relatively small until the 1980s when it was boosted by new strategies and an influx of drug money.
By the 1990s, the rebels were raiding military bases and launching attacks on major towns, but their advances were then reversed after U.S. aid was sharply increased.
Despite the focus on a military approach, many analysts say only a negotiated solution can put an end to nearly five decades of a war that has killed tens of thousands of people.
"There will be results against some structures, but it's not effective. It's expensive in relation to its gains. It's not sustainable," a Colombian security source said. "In the long term the FARC will adapt ... and a new strategy will be needed." (Editing by Daniel Wallis and Kieran Murray)
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