BOGOTA - 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 US 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.”