coming up at 6am on breakfast — sally nugent and jon kay will be here. i'm alpa patel. the top stories this hour: a lawyer for one of president trump's former aides, michael flynn, says he has offered to give testimony about alleged russian meddling in last year's us presidential election in exchange for protection from prosecution. south korea's ousted president, park geun—hye, has been arrested on corruption charges. they're the same charges that led to her political downfall, when the country's constitutional court backed a decision to impeach her. more us—led troops have arrived in poland in as part of nato's response to concerns over russia. they are part of the alliance's four battalions, aimed at giving reassurances to states unsettled by russia's actions in ukraine. a californian company has made history by launching a used rocket back into space. spacex has developed a way of landing its boosters, which are the most expensive part of a rocket, safely on earth after a mission.