Dr Fox said it was important to have "maximum flexibility" and said American or French aircraft would offer "a new capability".
Under the Strategic Defence and Security Review, the Navy will bear the brunt of the cuts: it will lose five warships and 4,000 personnel; Harrier jump-jets will be scrapped; and its flagship aircraft carrier, HMS Ark Royal, will immediately be retired.
The first of two new carriers will enter service in 2016, but will only be configured to carry helicopters - not jets - before being mothballed indefinitely, or sold once the second carrier enters service.
However, even when the second carrier arrives, the only aircraft likely to be able to use it will be American or French, with a new Joint Strike Fighter plane not due in service until 2020.
This means the Navy will not have British jets flying from its aircraft carriers for around 10 years and foreign pilots flying foreign aircraft will be vital to protecting Britain. But even they will probably not be able to fly off a British aircraft carrier until 2016 at the earliest.
Dr Fox said there would be increasing cooperation with the French after its president, Nicolas Sarkozy, recently decided to "engage more with Nato".
He insisted it was not unprecedented for Britain to have aircraft carriers without jets, pointing to a period during the 1970s and saying that there had been a "very limited" ability to fly fast jets from carriers in Afghanistan between 2004 and 2009.
"The concept of carrier strike is only one of the ways in which we have air power projection. We have Tornado, we have Typhoon and the military view at the moment is that because we don't have at the present time any problems with basing or overflights, then Britain is able to project air power in that way," he told BBC Radio 4's Today programme.
"The question is, could we guarantee that for 20 to 30 years, and of course we can't, which is why we are going to invest in the new carriers."
The Daily Telegraph reported today that ministers are to announce that one of the Navy’s new £3 billion aircraft carriers will never carry aircraft and will sail for only three years before being mothballed and possibly sold.
The Prime Minister will outline a timetable later today under which HMS Ark Royal is retired. The Navy’s other carrier, HMS Illustrious, will continue to function only as a helicopter platform stripped of jets before retiring in 2014.
The first of the new carriers, HMS Queen Elizabeth, will enter service in 2016, configured to carry helicopters, not jets. The second new carrier, HMS Prince of Wales, will arrive in 2019. At that point, HMS Queen Elizabeth will be put into “extended readiness”, effectively mothballed indefinitely.
On Trident and the expected delay on a decision about its replacement, Dr Fox added: "I do not believe that any of the measures that we take will in any way affect the effectiveness of our nuclear deterrent, nor our ability to have a continuous at-sea deterrent."
Professor Malcolm Chalmers, of the Royal United Services Institute, said there would be problems with morale on the new aircraft carriers because the Government has signalled it would have scrapped them if it could have done.
"The full message that's coming from the Government on the aircraft carriers is they wish they weren't in this situation, and if they could have cancelled them and saved a significant amount of money, they would have done," he told BBC Radio 4's Today programme.
"But I think there are going to be real difficulties with the morale of people operating that capability knowing that the Government doesn't really think they are that important."
