It's not clear whether Sean Penn knew of the missions he'd be asked to assume by Bolivia's President Evo Morales ahead of his visit to the country.
Cabinet chief Juan Ramon Quintana told reporters after Tuesday's meeting in La Paz that Morales asked Penn to defend the chewing of coca leaf before the United Nations, lobby Chile to restore Bolivia's long-lost access to the Pacific Ocean and help persuade the United States to extradite a former Bolivian president.
The Oscar-winning actor, 52, is already a goodwill ambassador for Haiti, where he has won respect for his post-earthquake charity work.
Asked by reporters about the missions he'd been asked to assume, Penn answered curtly.
"I am ambassador of Haiti," he said.
Penn later showed up for the start of a soccer match with Morales.