For world leaders an invitation to the Oval Office used to be a coveted prize.
Under Donald Trump it's become a ticket to a brutal political ambush.
South African President Cyril Ramaphosa became the latest victim in a long line that started with Trump's notorious row with Ukraine's Volodymyr Zelensky in February.
Trump has turned what were staid diplomatic "photo sprays" under his predecessor Joe Biden into punishing, hour-long tests of nerve in the heart of the US presidency, played out on live television.
