Russia's bobsleigh federation said female pilot Nadezhda Sergeyeva had tested positive for a "heart medicine" which is on the World Anti-Doping Agency's list of banned substances.
The White House said Trump had asked his eldest daughter -- who is also one of his top advisers -- to travel to Pyeongchang to lead up a "high level delegation".
The plucky West Africans finished 20th in Pyeongchang, more than seven seconds behind gold medallists Germany in a sport where success and failure is measured in hundredths of a second.
Zagitova was breathtaking in the Russian-dominated short programme, breaking the world record set just minutes earlier by her team-mate, 18-year-old Evgenia Medvedeva.
Ghana's hope for a medal at the 2018 Winter Olympics is lost after Akwasi Frimpong's first heat, but the Ghanaian appeared in style with a great helmet.
Svindal, 35 and coming to the end of a stellar career, clocked 1min 40.25sec down the 3km-long Jeongseon course to hand Norway its first ever Olympic downhill gold. He also became the oldest ever alpine skiing gold medallist.
Snowboarder Kim, 17, snatched the first of the day's eight gold medals in the women's halfpipe, while World Cup maestro Hirscher ended his long wait for a debut Olympic title.
Russia's bobsleigh and skeleton federation responded to more Sochi doping bans on Friday by saying they were prepared to take legal action against the International Olympic Committee.
The Rio 2016 cash-for-votes inquiry in Brazil has placed the International Olympic Committee under a fresh cloud of corruption less than a week before it is due to award the 2024 Games to Paris.
