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.

Syrian government, Kurdish-led SDF agree integration deal
Trump warns Britain on China ties as Starmer hails progress in Beijing
Israel releases 15 Palestinian bodies as truce deal shifts to next phase
WHO sees low risk of Nipah virus spreading beyond India
Trump, Democrats say deal reached to avert shutdown
Vietnam police seize tonnes of fake coffee products made from soybeans
Israeli fire kills two in Gaza as truce deal moves to next phase
Trump official says ICE in Minneapolis will be 'targeted,' vows changes on ground
