John Bolton has been called in to testify in the impeachment inquiry into US President Donald Trump.
The former National Security Adviser has been summoned by the House of Representatives investigators.
The US President is being investigated for pressuring Ukraine to investigate former US Vice-President Joe Biden and his son.
Trump denies the claims.
Bolton, who has spoken against the president on the matter, has been asked to testify on November 7.

Gaza building collapse: Rescue efforts end after 45 saved
US officials made rare Myanmar visit to free American businessman
Trump derides EU pitch to Canada as 'laughable', threatens more tariffs
Australia cracks down on student and backpacker visas to curb migration
EU plans social media ban for under-13s
