LA GABARRA, Colombia -- Maria, a wizened 57-year-old farmer's wife, lives in a plank-board shack in Santa Isabel, a village on the River of Gold that serves as Colombia's muddy border with Venezuela.
Shortly after breakfast one day last month, she and several dozen families watched grimly as Colombia's long war arrived swiftly along Santa Isabel's single dirt street. Violence has washed over the village for years, but never in the way she witnessed that sweltering March 21.
Maria and a dozen frightened neighbors said hundreds of guerrillas from the Revolutionary Armed Forces of Colombia (FARC) attacked their town from Venezuela, crossing the river to engage an anti-guerrilla paramilitary force occupying several riverside villages. Within an hour, Maria saw Venezuelan military aircraft swoop over her village to bomb paramilitary positions inside Colombia supporting the rebel advance.
If corroborated by the Colombian government, the bombings would be Venezuela's first military foray into Colombia's civil war. Now Maria and hundreds of others from Santa Isabel and neighboring villages along the border have fled south to this town, terrified that what they saw could get them killed. Colombian officials said they are investigating their account.
"Only the people who live there can serve as witnesses to this, and I am afraid," said Maria, who declined to give her last name for fear of reprisals. "Everybody where I live knows the guerrillas are on the other side of the river, that they maintain their camp there. Everybody knows this. Everybody."
Neglected by the government, too dangerous for Colombia's military, this wild frontier is emerging as a flashpoint that could complicate cooperative efforts to contain Colombia's war within its borders.
The 18,000-member FARC, engaged in a nearly four-decade war with the state, began an offensive late last month to retake this region rich in coca fields and strategic importance from the United Self-Defense Forces of Colombia (AUC). The paramilitary force fights the FARC alongside the Colombian army in much of the country. But here, say refugees and paramilitary commanders who do much of the fighting, they face a new adversary: the Venezuelan military.
According to accounts from a dozen refugees who have arrived here over the last two weeks to escape a fresh surge of fighting, Venezuelan military aircraft bombed paramilitary positions inside Colombia on March 21 and again a week later to the south in a way that helped a rebel scorched-earth campaign gain momentum across the northeastern frontier.
The result has been sharp recriminations between the two governments over who is responsible for keeping a widening civil war inside Colombia's 1,370-mile frontier with Venezuela.
President Alvaro Uribe has called on Venezuela to work harder to rid its side of a lightly governed frontier of the guerrillas, warning that "countries that allow terrorists inside their territory will end up as their victims."
On Wednesday, Venezuela rejected the allegations by border residents that its aircraft bombed the village. Vice President Jose Vicente Rangel dismissed the charges as "a grotesque lie" aimed at trying to discredit Venezuela's president, Hugo Chavez.
Chavez has acknowledged bombing targets last month but said the attacks occurred on his side of the border after a paramilitary "invasion" of Venezuelan territory. Once featured prominently in FARC propaganda posters as a kindred spirit, Chavez has blamed Colombia for the rise in selective killings and kidnappings on the Venezuelan side of the border.
In late March, Rangel accused the Colombian government of allowing paramilitary groups to operate "with absolute impunity" along a frontier that is frequently hard to identify on the ground. But Chavez has refused requests to allow Colombian troops to pursue guerrillas into Venezuela, prompting Colombian officials to wonder why Venezuelan military strikes seem to fall hardest on guerrilla enemies.
While Colombian guerrillas have operated along the Ecuadoran and Peruvian borders, nowhere has Colombia's war tested national boundaries more than in this battered region 310 miles northeast of the capital, Bogota. This frontier of rolling red-clay hills, thick jungle, coca farms and bloody history is known as Catatumbo for one of the slow, muddy rivers that weaves through it. The FARC made the region a key military objective after losing its 16,000-square-mile government-sanctioned haven in southern Colombia just over a year ago.
Colombian military officers here say the FARC, numbering roughly 800 troops in the region, is using Venezuela as it did its former sanctuary -- to stage attacks from a protected refuge -- in seeking to retake the region from paramilitary forces.
Between 1999 and 2000, the AUC carried out a series of massacres here that nearly wiped out civilian support in the former guerrilla stronghold. Hundreds of civilians were killed over several months and some of the bodies were tossed in the river to frighten those downstream. La Gabarra, a warren of abandoned homes and shuttered stores, shrank from 10,000 residents to 2,000 today.
The paramilitary group has since settled into a business partnership with residents, replacing the guerrillas as sole buyers of coca paste that they then sell to others who process it into cocaine. Now the FARC, eager to regain the coca proceeds and an important foothold along the northeastern border, is employing the same harsh tactics the AUC once used against them.
More than 500 people have fled at least a dozen villages in recent weeks, many of them gathering here on a wretched sports field where they are living on food donated from local supermarkets. No government relief has arrived. Nor has the army.
Many of their villages have been reduced to ash by the FARC, which set them on fire after giving residents five minutes to leave or face execution. Along the River of Gold, Maria and her neighbors chose a 12-hour walk to La Gabarra instead of a five-minute canoe ride into Venezuela because, she said, "the guerrillas there will kill us after years of living with the paramilitaries." Hundreds of others made the same choice.
On March 28, according to several refugees who fled the border hamlet of Monte Adentro, Venezuelan F-16s and OV-10s bombed paramilitary positions inside Venezuela and Colombia in what they believe was a response to a series of paramilitary forays into Venezuela in the preceding days. A day later, witnesses said, roughly 300 FARC troops arrived in Monte Adentro to burn it down.
"It is impossible that Venezuelan planes crossed the frontier," said Carlos Rodolfo Santiago, Venezuela's ambassador to Colombia, who acknowledged that the bombings targeted Colombian paramilitaries who he claimed attacked a Venezuelan National Guard post. "We observe international laws on the matter."
At one Venezuelan National Guard post across the River Catatumbo from the Colombian town of Tres Bocas, the mood was relaxed during a visit late last month despite reports of the recent attack upriver. Several soldiers, including the post commander, played dominos at a wooden table as bouncy Colombian music blared from a radio. Two M-60 machines guns sat unmanned in pillbox bunkers. A 60mm mortar tube, pointing toward Colombia, was covered with a dirty rag.
The Colombian army is also a scarce, static presence along these dirt roads. Soldiers guard bridges that span numerous rivers, an important oil pipeline, and the primary highways.
Col. Jose Alfonso Bautista, head of the military's Catatumbo Task Force, based in the municipal seat of Tibu 28 miles south of here, said his 800 men amount to one soldier for every 2.5 square miles of rugged territory. A military map sits on his desk, covered in red arrows that converge at points inside Venezuela that represent guerrilla camps and staging areas.
"Without passing judgment, it is a huge limit for us because just one foot inside and we can do nothing," Bautista said. "Right now this [offensive] is about the FARC retaking this territory. And they have a lot of terrorists trying to do so. The numbers are too big for us at the moment."
As a result, the defense of the region has been left largely to paramilitary forces. Emerging from thick dawn mists, several hundred paramilitary troops marched last month in a long, loose file on the road from Tibu to La Gabarra. Some appeared to be no more than 15 years old. The regional commanders occupy a row of wooden houses in El Mirador on the rise of a hill 10 miles south of La Gabarra. A commander wearing a Colombian Special Forces T-shirt, who is now responsible for repelling the FARC offensive, said Venezuela has become "a shield" to his enemy in a way that fellow AUC commanders have not seen in other border areas.
"The only government that has this position is President Chavez's -- not in Peru, not in Ecuador," said the commander, who called the recent bombing "clear support" for the FARC. One afternoon late last month, on the highway south from Tibu, a small FARC patrol appeared out of a narrow creek to stop traffic. They torched four trucks before shrinking back into the jungle, leaving the asphalt a singed, sticky mess. Now, an army patrol was here, standing in the shadows of the burned trucks. Asked how the guerrillas carried out the attack and escaped in broad daylight, a corporal waved his hand.
"They went that way," he said. "Toward Venezuela."