WASHINGTON - US President Donald Trump's latest threat to go ahead with 10 per cent tariffs on an additional US$300 billion (S$413 billion) of Chinese goods in September triggered a fresh wave of frustration from American businesses, who see themselves caught between two protectionist presidents and paying the price of their trade war.

They warned that the cost of the tariffs, which function as a tax on imported goods, would be passed on to consumers in the form of higher prices.