Siemens chief executive Joe Kaeser said US President Donald Trump is turning into a symbol of racism after telling four female Democratic policymakers to "go back" to where they came from. Mr Kaeser, one of Germany's most prominent business leaders, wrote on Twitter he finds it depressing "that the world's most important political office is turning into the face of racism and exclusion." “I lived in the USA for many years and experienced freedom, tolerance and openness as never before,” Mr Kaeser wrote, whose past jobs include a stint at a Siemens unit in San Jose, California. Mr Kaeser, 62, was replying to a sarcastic tweet by former German policymaker Ruprecht Polenz, who said Germany might end up having to take Mr Trump back. One of the president's grandfathers emigrated to the US in the 1880s. Mr Polenz, a member of Chancellor Angela Merkel’s Christian Democratic Union party, was commenting on Mr Trump’s campaign rally in Greenville, North Carolina, on Wednesday where his supporters directed chants of “send her back” at Representative Ilhan Omar, a Somali-born US citizen from Minnesota. Mr Trump attempted to distance himself from the chant, though he appeared to back off his disavowal on Friday.