this is bbc world news. our top stories. president biden prepares to announce that federal workers in the us need to get vaccinated, or prepare for an increase in testing. it comes as us covid cases continue to soar. us champion pole vaulter sam kendricks tests positive at the tokyo olympics the australian athletics team is isolating after close contact with him. the climate state we re in british scientists prove the past two decades have been warmer, wetter and sunnier than the average for the entire 20th century. the exiled belarusian opposition leader meets the us president at the white house, and gets a strong show of support.