SAN FRANCISCO - A little green leaf is causing big changes in Latin America.
To the U.S. government, the coca leaf is the central ingredient in cocaine, a dangerous and profitable drug that needs to be eradicated at its source: the coca fields of South America.
But to many Latin American indigenous people, the coca leaf is a medicine which they say should not only be allowed for traditional use, but rather promoted on the international market for its curative benefits.
Bolivia's Aymaran president, Evo Morales, has led the way in the push to return the coca leaf to its place as medicine, which it held in the Andes for thousands of years.
Since taking office, he has reversed the U.S.-backed ''zero coca'' policy and begun a new program that would eliminate cocaine production but focus on developing coca as a medicinal and nutritional product for the international market, with the goal of eventually declassifying it in the United Nations as a narcotic.
In other countries where coca has formed a part of the traditional diet and culture but is now used to feed the multi-million-dollar cocaine market, indigenous people have found themselves going up against national governments that have historically cooperated with U.S.-backed eradication policies.
In May, indigenous groups in Colombia protested the government's decision to limit the sale of legal coca products like drinks and ointments that had previously been sold in commercial outlets throughout the country to indigenous territories.
''The coca leaf and the traditional products that come from it are aligned with the ancient culture of the indigenous people of Latin America,'' healer Carlos Mamanche recently told the Venezuelan television station Telesur. The medical uses of coca, he said, ''are thousands of years old, older than Colombia, older than the United States who is behind all this.''
U.S. government officials have complained that despite Plan Colombia, more coca destined for cocaine production is being produced than ever before.
On May 14, Native groups in Argentina presented a proposal to the National Congress which would recognize coca on a national level for its ''importance in medicinal, nutritional, ritual, religious and social value.'' They claim corrupt government officials look the other way in sales of large amounts, but sellers of small amounts of coca are penalized.
In Peru, some 60,000 families depend upon coca production -much of it destined for the illegal market - for their livelihood. Efforts by President Alan Garcia to toughen coca eradication policies in April were met by resistance from coca farmers, who blocked roads in protest.
Peru, like Bolivia and Colombia, allows for the cultivation of the coca leaf for traditional and medicinal use.
A 1975 Harvard study found that coca is rich in iron, phosphorous, calcium, vitamin A and riboflavin. In 1995, the World Health Organization recommended further study of its potential health benefits.
Traditionally, coca, a mild stimulant and appetite suppressant, was one of the staples of the Incan and Aymaran culture. Spanish missionaries called the plant an agent of the devil, but Spanish landowners gave coca to the Indians they enslaved to make them work harder.
Today, indigenous people in the Andes continue to consider ''Mama Coca'' a sacred plant, a crucial part of a ceremony and ritual honoring Mother Earth and the spirits of the mountains.
Coca leaves are chewed or allowed to dissolve in the mouth, and are often combined with a mixture of an alkaline substance.
It is also used as a medicinal tea for stomach problems and altitude sickness, and as an anesthetic for wounds.
Critics of the U.S. eradication program say attempting to stop cocaine trafficking and addiction by eradicating coca is like eliminating barley or grapes to stop alcoholism. They emphasize that the coca leaf needs to be considered separately from cocaine in the international arena.
U.S. government officials disagree.
''There's really only one good use for the coca leaf in economic terms, and that's cocaine,'' the U.S. ambassador to Bolivia, Philip Goldberg, told The Associated Press.
On his recent visit to Colombia, President Bush promised to add billions more in coca eradication assistance to the $6 billion already spent on Plan Colombia.
The United States consumes about 50 percent of the 600 metric tons of cocaine produced annually.