The US once dominated global trade- after WW2 it was home to most of the worlds manufacturing capacity. At the same time is assumed global leadership in banking and money- the USD was established as the basis of the Breton Woods agreement. USA thus became the centre of the global financial markets. Even after the dollar/Nixon reneged upon the USDs central role under Breton Woods, as redeemable for gold, USA and the USD remained in place as central to the global financial markets. Since that time however USA has declined in importance as a trading nation- China today dominated global trade in manufactured goods and commodities. China is building its alternative trade payments network and increasingly trade is and will be denominated in Yuan- this process may still be gradual but there comes a point when a trend such as Chinas increasingly central role to global trade triggers a rapid decline in the central role of the USA and the USD. This is what Trump is seeking to delay, perhaps even prevent. His threats to BRICS nations if they continue to move away from USD denominated trade is recognition of the fragile and declining status of the USD. With Iran and Russia already selling their oil mostly for Yuan and Saudi Arabia joining the mBridge digital trade payments protocol the USD is close to losing its post Nixon petrodollar dominance.