The prime minister has expressed irritation at comments by military chiefs about the UK's role in Libya.
It comes after the RAF's second-in-command said "huge" demands were being placed on equipment and personnel.
David Cameron said: "There are moments when I wake up and read the newspapers and think: 'I tell you what, you do the fighting and I'll do the talking'."
He said military leaders were "absolutely clear" the mission could be kept going for as long as necessary.
"Time is on our side, not on Gaddafi's side," he said in a news conference.
He insisted that when he had spoken to airmen, morale and enthusiasm for the job was "extremely high".
Last week, the First Sea Lord, Sir Mark Stanhope, warned that continuing operations in Libya beyond September would mean taking ships away from other tasks.
And in briefing notes obtained by The Daily Telegraph and published on Tuesday, Air Chief Marshal Sir Simon Bryant, said morale among personnel was "fragile" and their fighting spirit was being threatened by being over-worked.
He said the service was being stretched by intense air operations in Afghanistan and the Middle East.
According to the briefing paper, ACM Bryant warned MPs in May that many areas of the RAF were "running hot", while service personnel's sense that the nation valued their efforts was being undermined by the government's defence cuts.
ACM Bryant said: "The true strength is in our people in continuing to deliver, despite all that's asked of them.
"Morale remains fragile. Although fighting spirit remains positive, this assessment will be challenged by individual harmony targets as Operation Ellamy [in Libya] endures [after September]."
He continued: "The impact of SDSR [strategic defence and security review] continues to undermine the sense of being valued. There is concern over the perceived lack of strategic direction which is restricting confidence in the senior leadership."
The RAF faces cuts of 5,000 personnel over the next three years - a reduction of almost 15%.
Shadow defence secretary Jim Murphy said the assumptions on which the government's defence review had been based were "fundamentally flawed".
"It is time to listen to military advice, review the review and provide our forces with capabilities which match our foreign policy ambitions," he said.
BBC defence correspondent Caroline Wyatt said the government's worry is that warnings of overstretch in the military are sending the wrong message to Col Gaddafi and Libya, as well as handing ammunition to Labour, which is calling for defence cuts to be reversed.
For the moment, there is no sign of a government u-turn on defence, but all three services are clear that there is very little in reserve for any new military mission as long as Libya and Afghanistan continue, she added.
Armed forces minister Nick Harvey said tough but necessary measures had to be taken in the strategic defence and security review but the MoD continued to have the resources it needed.
Meanwhile, George Osborne has said the Ministry of Defence will give an update on the cost of the Libya campaign in the next week.
Pressed by Ed Balls about the issue during Treasury questions in the Commons, Mr Osborne said the cost was being met by the Treasury special reserve and was "very much lower than the ongoing operation in Afghanistan".
The RAF is involved in a Nato mission to enforce a no-fly zone over Libya to protect civilians using "all necessary measures" short of a ground invasion.