The United States has launched a fresh offensive in its Latin American war on drugs by putting a $75m (£43m) bounty on the heads of 50 alleged leaders of the Colombian rebel group they accuse of running half of the world's cocaine trade.
Announcing the move against a group whom Washington calls "narco-terrorists", the US attorney general, Alberto Gonzales, said it was "the largest drug trafficking indictment in US history".
The announcement raised the prospect of US troops being sent into Colombia to pursue the rebels, a move that Mr Gonzales refused to rule out, although he insisted that there were other "effective options".
The Justice Department claimed that from its stronghold in the mountainous jungles of Colombia, Fuerzas Armadas Revolucionarias de Colombia (Farc) now accounted for 60 per cent of the cocaine smuggled into the US, worth over $25bn (£14.4bn), and 50 per cent reaching world markets.
Washington said Farc was also responsible for kidnapping, torturing and murdering farm workers who refused to co-operate.
The indictment comes as Colombia's centre-right President, Alvaro Uribe, seeks a second term - an ambition that he had to change the constitution in order to pursue. Mr Uribe is in effect the last of Washington's allies in the southern hemisphere, after a series of elections have swept left-wing politicians to power, from Hugo Chavez in Venezuela to Evo Morales in Bolivia.
The US is facing widespread opposition to its regional trade deals, and a Bolivian government that campaigned on the platform of legalising coca production.
The US invests an estimated $1bn across the region annually to combat the narcotics trade, much of which has been spent on military budgets and the eradication of coca leaves, the raw material for producing cocaine.
Any increase in the US military presence in Colombia could see Bogota further isolated from its neighbouring countries.
Of the 50 individuals charged by the indictment, 47 are currently at large. The US will seek the extradition of the three other Farc leaders who are already in custody. They are identified as Jorge Mendieta, Erminso Cabrera, and Juan Jose Martinez Vega.
This may improve the likelihood that the US Congress will extend funding for "Plan Colombia". This initiative, launched during the Clinton administration by the former Colombian president Andres Pastrana, calls for billions of dollars to eradicate Colombia's drug trade. It includes substantial US aid for the Colombian military.
But its effectiveness has been widely questioned. UN figures last year showed that coca production in the Andes region rose 3 per cent in 2004, suggesting that any decline in Colombia was more than made up for by increases in cultivation in Peru and Bolivia. Moreover, there has been scant change in either quantity or quality of the cocaine available in the US.
The Justice Department says that since the 1990s, Farc has switched from taxing cocaine producers in regions it controlled, to taking over production itself. It now sets prices for cocaine paste and runs jungle laboratories where the finished cocaine is produced and shipped to the US and other countries.
The 50 leaders, the indictment claims, collected millions of dollars in proceeds, using the money to buy arms to sustain its military campaign against the Colombian government.
Farmers who violated Farc rules were allegedly shot, stabbed or dismembered alive. Farc leaders also told their members to shoot down US planes spraying suspected coca crops with herbicides.
That fumigation policy is also controversial. Critics say that it also destroys legal crops.
President Uribe is riding high in the opinion polls ahead of May elections, largely on the back of a tough stance against Farc that has seen a significant decrease in the kidnap and murder rates, and improved security along the country's once notorious main roads.
However, Mr Uribe maintains a tight control over media outlets and uses a weekly television address to cultivate his image as an incorruptible leader.
The President's attempts to deal with right-wing paramilitary groups, who were previously deployed as a weapon against the Farc rebels, have been widely criticised by human rights groups. His controversial Justice and Peace law, aimed officially at demobilising the paramilitaries, has seen thousands of fighters escape prosecution over human rights abuses, and sparked fears that they have shifted to criminal activities instead.
Mr Uribe has so far resisted US attempts to extradite right-wing paramilitary members, who, like Farc, Washington accuses of participation in drug trafficking into the US.
The anti-drugs campaign
* The US has been engaged in international anti-drugs campaigns for more than a hundred years, following a deal signed in 1880 with China forbidding the shipment of opium between the two countries. Nixon coined the phrase "War on Drugs" in 1971, and the vast majority of federal time and money is now spent combating the drug trade in Latin and South America.
* Colombia isseen as the epicentre of today's war, as rebel groups supply most of the cocaine used in America. The US has funded coca eradication through private contractors, and helped train the Colombian armed forces to eradicate coca and fight guerrilla organisations.
* Critics say the war is unwinnable because of a lack of alternative crop options for poverty-stricken Latin American farmers, and America's appetite for cocaine. Rights groups accuse the Colombian government of atrocities in rebel areas.Reuse content