Nancy Obregon is leading the farmers in their struggle
BBC Radio 4's Crossing Continents was broadcast on Thursday, 6 November at 1100 GMT.
The programme was repeated on Monday, 10 November, at 2030 GMT.
Javier Lizarzaburu returns to his home country, Peru, to see the effects of the US war on drugs.
The US is spending more than $140 million in Peru this year to eradicate coca, the raw material from which cocaine is made.
PERU'S COCA PRODUCTION
Santa Rosa del Mishoyou is one of Peru's coca producing areas
But coca production is on the increase. And now for the first time, the desperately poor coca farmers - led by their new charismatic leader, Nancy Obregon - are making their voices heard in the capital, Lima.
Javier travels to a remote region in the Amazon rainforest to meet Nancy and hear her case against the US-backed policy of forced coca eradication.
And he also travels to Washington to ask top officials whether they can win the war against drugs in Peru.
Producer: Sue Ellis
Presenter: Javier Lizarzaburu
Editor: Hugh Levinson