Chief of Staff General David Goldfein raised the prospect of elite troops travelling on a mothership to anywhere in the planet within an hour.
He referred to Sir Richard Branson's company Virgin Galactic, which plans to make intercontinental space travel a reality.
The entrepreneur has announced plans to launch people into space in 2018, with the first test flights beginning this year.
He is convinced that eventually the costs of space flights will come down and the fuel savings on intercontinental flights using a low Earth orbit will make travel from one place to another commercially viable.
He said: 'The question for us is what does that mean if I take seven special operators, put them on this and then can get to any place on the planet in less than an hour?
'What does that do to us and what does that do for us in terms of all of the scenarios that we think our way through?
'This is the technology that commercial industry is now going for. With all of the challenges that we have talked about there is such opportunity for us if we can just jump on it and grab it.'
Also speaking at the conference, Defence Secretary Sir Michael Fallon said young people needed to be reminded of the stories of Britain's 'great inventors and imagineers'.
