Conservative critics of President Obama’s mission in Libya have been loudly insisting that he pursue “regime change” as the mission’s chief goal, but Obama and his advisers have steadily rebuffed that demand. Yesterday, for instance, Obama stated that while “it is U.S. policy that Gaddafi needs to go,” the UN authority does not enable the U.S. to target Libyan dictator Moammar Gaddafi directly.

“When it comes to our military action, we are doing so in support of UN Security resolution 1973 that specifically talks about humanitarian efforts, and we are going to make sure we stick to that mandate,” Obama said.

So does the United States or its coalition partners have the authority under the resolution to kill or remove Gaddafi? The question has been the subject of contention for coalition members. British defense secretary Liam Fox stated that coalition members were trying to eliminate Gaddafi, but he was later contradicted by a top general. So what gives?

After speaking to a number of experts, the answer is: It depends on the circumstances.

“The key phrase in the UNSC resolution is ‘all necessary means,’ which is very broad and allows significant discretion to the participating countries in determining their military objectives in enforcing the resolution,” said Ken Gude, a national security expert with the Center for American Progress, “which could certainly include targeting the Libyan command-and-control structure, including Gaddafi.”

Kenneth Anderson, a law professor at American University’s Washington School of Law, said that even absent the UN resolution, targeting Gaddafi was fair game.

“Even if a civilian — which Gaddafi is not, in any event — a leader in command of the military forces is a civilian taking part in hostilities and may be targeted, other things being equal,” Anderson said. “Taking part in hostilities does not require carrying a weapon or engaging directly in fighting; commanding forces is certainly enough.”

However, Robert Chesney, a professor at the University of Texas who served on the Obama administration’s detainee task force, said that interpreting the UN resolution as a license to kill Gaddafi would be a stretch.

“Should Gaddafi happen to be in an air defense-related command-and-control bunker at the wrong time, there’s no obligation not to attack it because of his presence,” Chesney said, adding that neither the sections on protecting civilians or authorizing the no-fly zone explicitly authorized regime change. “Surely the resolution would have said regime change if that’s what it meant.”

Of course, mere legal authority may not be the primary factor driving the thinking of Obama officials. Rather, the adminstration’s statements on the parameters of the mission may be more a reflection of diplomatic and strategic considerations. The perception that the mission is about regime change, rather than humanitarian intervention, risks alienating key partners. Defense Secretary Robert Gates told reporters on Sunday that “this is a very diverse coalition,” adding: “If we start adding additional objectives then I think we create a problem in that respect.”

The administration’s decision to avoid stating they are targeting Gaddafi specifically has led to charges that the mission itself is ill conceived, given that stopping Gaddafi and helping the rebels is the implicit goal of intervening. But the fine line they’re walking on whether or not they are attempting to kill or oust Gaddafi may be crucial in terms of keeping the coalition together.