US e-commerce giant Amazon has expanded its "Prime Day" promotional event this year to four days, in a bid to give shoppers "more time to shop and save". US President Donald Trump's global trade war has increased the threat of higher prices for US shoppers. While forecasts show another record year for sales, other indicators are highlighting cautious consumer sentiment. Also in this edition: Trump's 50 percent tariff threat on all copper imports could hurt global producers like Zambia.