By Daniel Schweimler
BBC News, Quito
Ecuador and Venezuela's presidents have both mobilised troops
South America is living through one of its worst diplomatic and political crises for many years.
Troops have been mobilised and ambassadors withdrawn, while frantic negotiations are going on in Washington and several Latin American capitals to try to deflate the tension.
Most in Colombia celebrated when their troops last weekend killed Raul Reyes, the second-in-command of the Revolutionary Armed Forces of Colombia (Farc) guerrilla movement they have been battling for more than 40 years.
The Colombian soldiers also killed another 20 or so rebels and captured computers belonging to the commander, which their government later said contained vital information.
The problem was that the raid was carried out just over the border, in neighbouring Ecuador, where Farc rebels often rest in the dense jungle.
Ecuador was outraged, calling the attack a gross violation of its sovereignty.
Most of Latin America agreed, led by the radical Venezuelan president, Hugo Chavez.
Both Venezuela and Ecuador withdrew their ambassadors, and sent troops to their respective borders with Colombia.
Colombia was isolated at the Organisation of American States
Some feared military conflict - but then the negotiations began.
The Organisation of American States, whose aim is to solve conflicts in the region, said Ecuador's sovereignty was violated.
The Ecuadoran president, Rafael Correa, went on a regional tour to explain his position.
He wants a stronger international condemnation of the Colombian attack, and for his neighbour to issue a more comprehensive apology than the one it has given so far.
Colombian officials said the captured computers contained evidence that both Ecuador and Venezuela collaborated with the rebels - something both governments denied.
Ecuador says that last year it destroyed 47 Farc bases on its territory.
This is a dispute about hurt national pride and long-standing regional rivalries.
With national pride hurt, soldiers are gathering on Ecuador's borders
However, Ecuador, Colombia and Venezuela are major trading partners and simply cannot afford to go to war.
Tens of thousands of Colombians live in Ecuador, and Venezuelans in Colombia.
Once acceptable apologies have been issued, the tension is likely to subside.
President Uribe of Colombia has already said he will not order any kind of similar military operation.
People in all three countries are marching for peace.
But this dispute has grown from the changing political landscape in Latin America.
Since he came to power in 1998, Hugo Chavez of Venezuela has constantly criticised the United States and sought to increase his influence over the region, lubricated by his country's vast oil wealth.
He now counts Bolivia, Ecuador, Nicaragua and Cuba among his strongest allies, while he is on good terms with Argentina, Chile and Brazil.
The US can count only on Colombia's President Uribe as a loyal friend, and sends the country billions of dollars a year to help in the fight against the cocaine industry.
President Chavez calls Mr Uribe "Washington's poodle".
Some in Colombia accuse Mr Chavez of trying to destabilise the region.
While this dispute is likely to subside over the next few days and weeks, Colombia's war against its Farc guerrillas is far from over, and the jockeying for influence between the United States and Venezuela over the region will continue.