beijing china foreign ministry wednesday say china fully strictly implement u.n. security council resolutions north korea investigate activities contravene resolutions china uphold resolve north korean nuclear issue via talk ministry spokeswomen hua chunying add speak regular news brief beijing u.s. president donald trump ask china cut financial link north korea abide u.n. sanction meet chinese president xi jinping beijing senior white house official say wednesday trump arrive beijing wednesday afternoon south korea two-night stop chinese capital part marathon asia tour china say investigate u.n. resolutions north korea contravene