The United States sees drug abuse as a public health problem as much as a crime issue and is seeking to learn from countries in Europe and elsewhere about how to treat addiction as a disease, Barack Obama's drugs policy chief Gil Kerlikowske said. He noted what he described as a "somewhat successful" fresh approach in Portugal, where since 2001 authorities have dispensed with arrests, trials and prison for people carrying a personal supply of any drug from marijuana to heroin and focused their efforts on prevention messages and treatment.