denying a claim in the book he asked defense secretary james mattis to assassinate the leader of syria. >> i heard somewhere where they said the assassination of president assad by the united states. never discussed. >> reporter: trump claiming today it was time to disrupt the confirmation hearing for his supreme court nominee brett kavanaugh. >> it was put out to interfere in my opinion at this time with the kavanaugh hearings. >> reporter: behind closed doors, trump saying he suspects the normal national security adviser mcmaster and former treasury adviser cohn made the claims. >> i think probably from disgruntled former employees. you have people like general mattis, general kelly, two american heroes calling the book pure fiction. i would rather take the word of those two individuals than a couple of disgruntled former employees that are anonymously