A Syrian defector was told to hide his face while testifying to US Congress about the horrors of the Assad regime amid fears Tulsi Gabbard would leak his identity, according to former state department officials.

Ms Gabbard, an Iraq war veteran accused of echoing Russian and Syrian propaganda, is facing a battle to secure her nomination to the post of Director of National Intelligence (DNI).

On Thursday, she will appear before the Senate intelligence committee, which could complicate her path to the role by sending her on to a full vote in the Senate without its approval.

Donald Trump reportedly views Ms Gabbard as the most vulnerable in his slew of unorthodox cabinet appointments.