The Falkland Islands Defence Force (FIDF) is a locally maintained volunteer defence force unit, funded by the Falkland Islands Government, working alongside the UK military units based at Mount Pleasant, to ensure the security of the islands. Falkland Island nationals, British citizens, British overseas citizens and Commonwealth citizens aged between 17 and 55 are eligible to apply to join the FIDF. According to the 2006 Falkland Islands census, approximately 1,600 men and women may have been eligible to apply to join the FIDF, subject to medical clearance and selection procedure.