Brussels: NATO allies are weighing when to call an end to the air campaign in Libya now that Muammar Gaddafi's forces are surrounded and often beyond the reach of Western warplanes, officials said on Thursday.
Forces loyal to the deposed dictator are encircled in Sirte and Bani Walid and hiding among the local population, rendering NATO fighter jets less effective and raising the risk of civilian casualties, officials said.
"The effect of air power is not necessarily the right tool with these kind of threats," a Western official, who spoke on condition of anonymity said.
Gaddafi's loyalists, who had once rolled across open desert in trucks and tanks, are no longer a natural target for NATO aircraft as they shelter in built-up areas.
"You can't hit something that's not there," the official said. "A sniper on a rooftop, that's not really something we would go after (with air power)."
Reflecting a shift in the war, the number of NATO air strikes has dramatically declined in recent weeks, with only one bombing raid reported on Wednesday compared with about 15-20 air strikes a day earlier in the conflict, NATO officials said.
NATO Defence Ministers meeting in Brussels on Thursday and Friday are discussing how and when to call time on the six-month campaign, which has been credited with turning the tide in the conflict and forcing Gaddafi into hiding.
Allied air strikes began in March when Gaddafi's soldiers had rebels on the back foot, and helped tip the balance in favour of a loose coalition of Gaddafi opponents who overran the capital Tripoli in August, winning international recognition.
Supreme Allied Commander Admiral James Stavridis was due to offer his assessment of the air war as NATO Secretary General Anders Fogh Rasmussen said he was "encouraged by progress" in the campaign.
Rasmussen said the decision to halt the operation would hinge on the ability of National Transitional Council (NTC) forces to maintain order and not the fate of Gaddafi.
"The termination of the operation is not dependent on Colonel Gaddafi," he told reporters.
"We will carefully assess the security situation and in particular, of course, take into account the capability of the National Transitional Council to protect the civilian population effectively."
Officials said the alliance had to make a political judgement, balancing the need to prevent attacks on civilians while avoiding the impression of meddling.