US President Donald Trump has sparked concern for Australian defence companies after he threatened to pull back international supply chains for parts of the F-35 Joint Strike Fighter program in favour of domestic manufacturing.

Speaking to ABC, Brendan Thomas-Noone, Research Fellow in the United States Studies Centre's Foreign Policy and Defence Program, said the Joint Strike Fighter program was designed to bring in as many partner countries as possible and separating those supply chains would be "incredibly difficult".

"If they were to follow through on this it would make the plane eye-wateringly expensive and cost-prohibitive."