The RAF is planning on the basis that operations over Libya will last at least six months, its chief has said.
Air Chief Marshal Sir Stephen Dalton warned the service would need "genuine increases" in its budget to run the range of operations ministers demand.
He told the Guardian that without more investment, the RAF would struggle to maintain levels of capabilities.
The Army and Royal Navy will set out details later of the first wave of job losses from October's defence review.
Ministers have denied the review is simply a "cost-saving exercise".
Sir Stephen said his assumption was that the RAF's warplanes and surveillance aircraft would be needed over Libya for a number of months, rather than weeks.