Almost three months into the campaign of air strikes, Britain and its Nato allies no longer believe bombing alone will end the conflict in Libya, well-placed government officials have told the Guardian.
Instead, they are pinning their hopes on the defection of Muammar Gaddafi's closest aides, or the Libyan leader's agreement to flee the country.
"No one is envisaging a military victory," said one senior official who echoed Tuesday's warnings by Admiral Sir Mark Stanhope, head of the navy, that the bombing cannot continue much beyond the summer.
Stanhope, whose comments caused fury in Downing Street, was expressing publicly what many senior defence officials say in private, officials made clear.
The conflict is also straining relations between Washington and its European allies. Although few Nato countries are taking part in the air strikes, Europeans – including the British – are dismayed at the refusal by the US to deploy its low-flying A10 "tankbusters" and helicopters. The UK has deployed four Apaches, the French 12 attack helicopters. There are 150 other attack helicopters in Nato which can operate from ships but they all belong to the US Marine Corps, said Brigadier Benjamin Barry, senior fellow at the International Institute for Strategic Studies (IISS).
The latest tension between Nato allies follows a withering speech in Brussels last week by Robert Gates, the outgoing US defence secretary, who referred to the "spectacle of an air operations centre designed to handle more than 300 sorties a day struggling to launch about 150".
The problems within Nato are mirrored among rebel fighters on the ground in Libya. In Misrata the militia leaders, few with military experience, have failed to coalesce into a co-ordinated army which can undertake manoeuvre operations. A second obstacle to an advance is the lack of heavy weapons which would allow them to punch through the ring of Gaddafi forces facing them – and then hold that ground against counterattacks.
While some militia leaders have told their troops to dig in, others have refused, leading to troops facing artillery fire out in the open. The result, last Friday, was slaughter; after British Apaches launched their first attacks on the Misrata front the night before, Gaddafi's forces hit back with an unprecedented barrage of thousands of Russian-made Grad rockets. The Apaches did not reappear in daylight to attack the rocket launchers and rebel units suffered 31 deaths and 120 other casualities.
The absence of Apaches dismayed rebel units, not all of whom are sure of Nato's motives in failing to offer co-ordinated air support. None will say so publicly, but some commanders say the alliance may want Tripoli to rise up against the dictator, rather than be "liberated" by rebels from elsewhere – an event that could trigger political infighting in the postwar period.
One member of the Misrata military council complained that some commanders had suggested it would be better to have a lightly-held first line with a defensive belt a kilometre or two behind it – a standard tactic for professional armies. "It's a good idea," he said. "But nobody wants to be on the second line." A rebel logistics officer, Suleiman Abfalga, said: "We cannot live in holes in the ground, we have to show we are not afraid."
It has emerged that Nato has been dropping leaflets threatening Apache air strikes against government forces. The leaflets – each featuring a picture of an Apache helicopter and a burning tank along with the words: "If you go on killing the children and families you will be destroyed" – were sprinkled from a bomb that detonated above no-man's land east of Misrata, raining down over rebel units who had advanced beyond the frontline without telling Nato.
Political considerations among rebel leaders are also having an impact, preventing an order to assault Zlitan, the next town on the road to Tripoli: longstanding grievances between the two populations plus a fear of killing civilians – have seen Misrata's units refuse to attack until Zlitan's own rebels rise up – a problematic exercise given that Zlitan is home to the 32nd Brigade, one of Gaddafi's few elite formations.
Gaddafi's problems are the reverse of those facing the rebels. He has vast stocks of Grad missiles, but his troops are demoralised by what one British source described as "incremental attrition". One Nato official observed: "Defiance can only be measured by loyalty." He expressed the view that the conflict was "close to the tipping point".
Sources told the Guardian that indictment for war crimes against Gaddafi and his inner circle before the international criminal court can be put on the back burner, in the hope this would encourage the Libyan leader to seek sanctuary in a friendly African country.
There is concern, meanwhile, that the longer the conflict goes on, the greater the risk of civilian casualties as Nato commanders succumb to political pressure to step up the bombing campaign. "The longer the war goes on the greater the chance of a blunder resulting in significant civilian casualties," warns the IISS in its latest Strategic Comments. It adds: "The risks also increase of both the government and rebels becoming more radicalised and perpetrating war crimes."
The IISS warns that fighting could spill over into Tunisia. Increasing instability in the Middle East, such as the current crises in Syria and Yemen, could compete for strategic attention and military resources. Other problems spring from the flight of nearly 1 million people so far from Libya to neighbouring states and Europe. "Any of these factors, either individually or in combination, could weaken the coalition's military strength and political resolve."
Of the 10,000 sorties flown by Nato aircraft since mid-March, around one-third have been conducted by aircraft able to attack ground targets. This is far fewer than those flown over Serbia and Kosovo in 1999. The MoD says British aircraft have been involved in 400 strike sorties, dropping some £80m in weapons, according to official figures released to MPs.
