By David Brunnstrom
BRUSSELS (Reuters) - The Dutch defense minister warned NATO allies on Wednesday against "mission creep" in Libya and forecast heated debate in the military alliance about the future of its campaign if it was not over by the end of September.
Hans Hillen called NATO allies who had thought bombing would force Muammar Gaddafi to step down "naive" and said a political solution was needed, underscoring deep divisions in the alliance about a campaign of air strikes launched in March.
"I hope we will be finished by the end of September," Hillen told reporters on the sidelines of a security conference in Brussels, when asked about NATO's decision to extend its mission by another 90 days from Wednesday.
"If it's not finished by then, I think the debate will get higher and higher -- 'why didn't we finish until now', and 'what is the problem exactly', and 'why does everybody say give us three more weeks, three more months?'"
"And then in November they say, 'well, just a couple of months' -- that's mission creep."
Hillen said NATO's mission should be confined to its U.N. mandate to protect civilians.
"If it changes into driving out a dictator, then the question is whether NATO should accept this as a new task."
Hillen responded to a call this month by outgoing Defense Secretary Robert Gates for the Netherlands and other NATO allies who are not talking part in the bombing campaign to do more in Libya, saying it was "contributing fairly."
It was already providing a minesweeper for the naval operation and air-to-air refueling for the air operation, he said, adding: "We were not the ones who pushed it -- the bombings."
Hillen said some allies had underestimated the task.
"Libya is a very, very big country indeed. People who thought that merely by throwing some bombs it would not only help the people, but also convince Gaddafi that he could step down or alter his policy were a little bit naive," he said.
"Libya is too big and all the military goals too big ... The solution should be a political solution and the military only helps to achieve this and the question is: 'how long will you push on the military side if the political one doesn't move?'"
Dutch Prime Minister Mark Rutte said the Netherlands was "fully committed" to the mission in Libya and that it was a "pity" that not every country contributed to such operations.
"It is true that not all countries are involved (in Libya), such as in Afghanistan. We'd like to have all countries involved every time, but it doesn't always work like that," Rutte told reporters in The Hague.
"We are fully committed to taking our responsibility there."
While NATO has stressed the need for a political solution, its members have been divided by those led by Britain and France who have been active in the bombing campaign and those who have doubted this policy and played only a supporting role.
Hillen's remarks came after Italy's foreign minister rattled allies last week by urging a ceasefire in Libya.
NATO says it will continue its mission as long as it takes, but with only eight allies talking part in air strikes, it has expressed concern about the campaign's sustainability unless others do more, a call that has fallen largely on deaf ears.
Jean-Francois Bureau, a senior official in the French defense ministry, told Reuters it was difficult to say how long the campaign would have to be sustained.
"September, or the end of the year, I don't know, frankly," I cannot say, but ... I believe that for all the nations taking part in this mission, that we cannot give up," he said.
Bureau said the mission showed the need for European countries to make up shortfalls in capabilities such as air-to-air refueling tankers and surveillance planes.
"Once you have begun a process like the one initiated in Libya ... nobody knows how long it will last, but we must be ready to fulfill the mission whatever the time needed, so sustainability is something we must take care of," he said.
Bureau said the French carrier Charles de Gaulle, from which aircraft have been flying up to 40 percent of the Libyan strike missions, would have to be withdrawn by the end of the year as it had been on almost continuous operations for 15 months.
"Beyond this year, it's true we would have to look at other options... but I think we will fulfill the mission," he said, explaining that France would be able employ land-based bombers.
(Additional reporting by Gilbert Kreijger and Aaron Gray-Block in The Hague, Editing by Rex Merrifield and Sonya Hepinstall)