Stocks plunge as China ignites currency weapon in trade war with US

Australian shares plunged nearly three percent at the open of trade this morning after Wall Street suffered its worst day this year following a sharp escalation in the US-China trade war. 

China has ignited its currency as a weapon against US tariffs amid speculation that the Peoples Bank of China might consider selling down US Treasury notes in retaliation. 

ABC's Peter Ryan has been following the drama on markets.