 As CAS , Hancock worked to enhance the RAAF 's deterrent capability in the Pacific region , particularly in light of heightened tensions with Indonesia during its period of Konfrontasi with Malaysia . In June 1963 , Hancock undertook a mission to Britain , France and the United States to consider potential replacements for the English Electric Canberra bomber as Australia 's prime aerial strike platform . After investigating the US " TFX " , North American A @-@ 5 Vigilante and McDonnell Douglas F @-@ 4 Phantom II , the British BAC TSR @-@ 2 , and the French Dassault Mirage IV , Hancock decided that the swing @-@ wing TFX , forerunner of the General Dynamics F @-@ 111 , would be the aircraft best suited for this role . However , as the TFX had not yet flown , he recommended purchase of the already operational Vigilante to counteract a perceived imminent threat from Indonesia . In the event , the Federal Government did not go ahead with an immediate replacement for the Canberra , and Hancock 's original choice of the TFX was taken up as a long @-@ term solution , leading to Australia 's agreement in October to purchase the F @-@ 111C . The same month , as Konfrontasi continued to simmer , Hancock approved simplification to the rules of engagement for Australian CAC Sabre fighters based at RAAF Butterworth to engage and destroy Indonesian aircraft violating Malay air space . The following month he urged using RAAF Canberras from Butterworth to make pre @-@ emptive strikes against Indonesian air bases , in retaliation for incursions into West Malaysia , but Britain , which had initially requested Australia 's involvement , held back on action . 
