It took just one 50-minute speech by US President Donald Trump to undermine global economic stability and raise the prospect of a recession, with China's countermeasures only amplifying the risk of a debilitating tit-for-tat trade war. But it said things could get worse if a tit-for-tat trade war began, and on Friday China announced retaliatory tariffs on US goods of 34 percent.

US President Donald Trump's widest-ranging tariffs to date took effect Saturday, in a move which could trigger retaliation and escalating trade tensions that could upset the global economy.