Allende began to fear his opponents, convinced they were plotting his assassination. Using his daughter as a messenger, he explained the situation to Fidel Castro. Castro gave four pieces of advice: convince technicians to stay in Chile, only sell copper for US dollars, do not engage in extreme revolutionary acts which would give opponents an excuse to wreck or control the economy, and maintain a proper relationship with the Chilean military until local militias could be established and consolidated. Allende attempted to follow Castro's advice, but the latter two recommendations proved difficult.