The Big Question: Why has Colombia invaded Ecuador, and why is Venezuela joining the fight?

(Independent Graphics)

Why are we asking this now?

At the weekend the Colombian army crossed the border into Ecuador to kill a Colombian rebel leader, and 16 other guerrillas, who were sheltering there. The move outraged the government in Ecuador, which broke off diplomatic relations with its neighbour and helicoptered 3,000 of its own troops to the border area.

Colombia's other neighbour, Venezuela, also reacted. It also expelled Colombia's diplomats and ordered thousands of troops, tanks and fighter jets to the border. Venezuela's fiery president, Hugo Chavez, also warned that war could break out if Colombia crossed into Venezuelan soil. It is the worst diplomatic crisis in Latin America for many years.

So what really happened?

The Colombians say they first bombed a rebel camp on their own side of the border. They claim that rebels hiding across the border in Ecuador fired on them, so they crossed the border to fight back.

The Ecuadorean president, Rafael Correa, called that account an outright lie: "It was a massacre," he said. The Colombian troops were backed by military planes, suggesting the raid was pre-ordained. When Ecuadorean troops reached the rebel camp they found the rebels were killed in their sleep "in their pyjamas". The rebels were "bombed and massacred as they slept, using precision technology." Colombian military sources seemed to corroborate this by revealing that US intelligence helped target the rebels by disclosing that the rebel's deputy leader, Raul Reyes, was sporadically using a satellite telephone, whose signal could be pinpointed.

What's at the heart of the dispute?

In Colombia a left-wing group of rebels called the Farc – the Revolutionary Armed Forces of Colombia – has been fighting the government for more than four decades. Their declared aim is a fairer wealth distribution in the country, which has a huge divide between rich and poor. But they finance their armed struggle by trading in cocaine and political kidnapping. Their base is in the remote rural regions of the country but they also take shelter in Ecuador and Venezuela which each have a porous border over a thousand miles long with Colombia. The Colombians accused their neighbours of turning a blind eye to the rebels' presence – something Ecuador and Venezuela deny.

What's the position of the three leaders?

Colombia is ruled by a right-wing populist, Alvaro Uribe, a Harvard-educated lawyer who is a staunch ally of the Bush administration. Since coming to power in Colombia in 2002 he has maintained a hardline policy against the Farc rebels, who killed his father during a kidnap attempt. Washington has poured billions of dollars in American aid to support the Colombian military. The president in Ecuador is a young left-wing economist, Raphael Correa. He has not minced his words in the current crisis. Colombia, he said, has "a foul and lying government that doesn't want peace." In Venezuela the charismatic leftist president Hugo Chavez, backed by his country's vast oil reserves, is attempting direct the continent away from the influence of Washington. He called Colombia "a terrorist state" and described President Uribe as "a criminal," acting for "the United States empire". By contrast he called Raul Reyes a "good revolutionary".

What were the rebels doing?

The Colombians claim they have captured the computer of Raul Reyes, who was the rebels' main interlocutor with foreign governments. It reveals, they claim, growing ties between rebels and Venezuela and Ecuador. One document, it was said, showed that President Chavez had provided $300m to the FARC. In another letter the rebels offered military assistance to Venezuela in the event of a US attack. A third, it was claimed, showed that the rebels were in negotiations for 50 kilos of uranium to build a dirty bomb. Venezuela and Ecuador poured scorn on the Colombian claims. Journalists were not given copies of the alleged documents.

Why is the US involved?

As much as 90 per cent of all cocaine on American streets comes from Colombia, the centre of the world cocaine trade. Since 2000, the US has spent more than $4bn giving Colombian forces training, equipment and intelligence to hunt down drug-traffickers and eradicate coca crops. Since 2002 the Bush administration has conceded that some aid is now being spent to tackle the insurgency, even though there is evidence that all sides in Colombia are involved in drug-trafficking. Venezuelan officials insist they have information about links between drug traffickers and top Colombian officials.

The Colombian government has also played into American paranoia about the "war on terror", characterising FARC not as an armed struggle to bring political change in a highly segregated society – split between rich families of Spanish descent and the vast majority of poor Colombians, many of whom are of mixed race – but as an arm of international terrorism.

What do other countries in theregion think?

They are worried. The big regional heavyweight, Brazil, which has mainly cordial relations with the three presidents involved, has demanded Colombia apologise to Ecuador. Brazil fears the conflict is beginning to destabilize regional relations. The president of Argentina is due to visit Venezuela tomorrow. Peru has urged restraint. Mexico and Chile have offered to mediate.

Could there befull-scale war?

Certainly the rhetoric is supercharged. Hugo Chavez has called Colombia's President Alvaro Uribe a "mob boss" and a liar. "If it occurs to you to do this in Venezuela, President Uribe, I'll send some Sukhois" – the 24 warplanes he recently bought from Russia. The President of Ecuador has said: "This is not a bilateral problem, it's a regional problem... Should this set a precedent, Latin America will become another Middle East."

But there is little appetite for armed conflict. The economic costs would be too high. Trade between Colombia and Ven-ezuela is worth $5bn a year, with food imports vital to Venezuelans suffering milk and meat shortages. Ecuador depends on some $1.8bn in trade with Colombia. Militarily Colombia is a formidable foe, thanks to $5bn in aid from Washington and US military advisers sprinkled throughout the Colombian army. The signs are of a climb-down. Colombia has indicated that it will not send more troops to its borders. And Washington, while backing Colombia's right to defend itself, has urged dialogue.

Was Colombia justified in crossing into Ecuador to kill rebels?

Yes...

* The FARC rebels are the chief drug traffickers in a country which produces most of the world's cocaine

* Rebels were being given covert support by both Ecuador and neighbouring Venezuela

* The rebels are major movers in international terrorism with plans to build a dirty radioactive 'dirty' bomb

No...

* It was a clear violation of the sovereignty of a neighbouring nation, and was bound to cause regional instability

* The rebels are not international terrorists, as Colombia claims, but leftists who want a fairer distribution of resources in the country.

* The real drug barons are not the rebel leaders but criminal gangs, many of whom have associations with the Colombian government