washington u.s. treasury secretary steven mnuchin thursday pledge treat seriously business deal president donald trump family might foreign company flag officials national security risk mnuchin say case exist senior democrat press mnuchin appearance senators produce list trump family business relationships foreign company senator sherrod brown top democrat senate bank committee say mnuchin adequately respond march letter ask treasury list trump business partner see sanction list investigate national security watchdog analyze foreign investments treasury release copy march 31 letter respond brown say department work agencies address mitigate potential conflict interest arise mnuchin say review case committee foreign investment unite state cfius every week treasury lead department among government agencies part cfius assure case involve president members family would treat seriously would review would anything else mnuchin tell senate panel trump wealthy real estate developer decline sell global businesses despite demand critics avoid conflict interest trump say two old sons daily control businesses president reuters review march find least 63 individuals russian passports address buy least 98.4 million worth property seven trump-branded luxury tower southern florida u.s. treasury vow special treatment trump investment review