Westminster is increasingly concerned by the inability of NATO to resolve the conflict in Libya. Military theorist Carl von Clausewitz once wrote: ‘No one starts a war – or rather, no one in his senses ought to do so – without first being clear in his mind what he intends to achieve by that war and how he intends to conduct it.’ I supported David Cameron’s no-fly zone initiative in Libya, but the UK is fighting a new protracted war with conflicting objectives. The Libyan opposition is unable to take significant territory from Colonel Gaddafi’s professional forces and, while weakened by the NATO air offensive, Gaddafi’s forces show no signs of giving up. Nobody seems keen to arm the rebels or deploy ground troops to break the deadlock.

Britain’s armed forces are engaged in combat operations which seemed unthinkable just a few months ago. Until recently, Mr Cameron seemed to aspire to a different kind of foreign policy from his predecessors. He initially ridiculed the idea that ‘you can drop democracy out of a plane from 40,000 feet’. But now the Foreign Secretary argues that it is ‘against our values’ to ‘turn a blind eye’.

David Cameron, Nicolas Sarkozy and Barack Obama say the Libyan operation will continue until Gaddafi goes. The weeks roll by but there has still been no clarity on how we will achieve that objective. ‘Regime change’ is manifestly not part of the UN Security Council resolution which the three leaders sought and obtained. The British Chief of Defence Staff, General Sir David Richards, argues: ‘If we do not up the ante now there is a risk that the conflict could result in Gaddafi clinging to power.’ The Foreign Secretary, meanwhile, told Parliament in mid-May that the government has always argued for the ‘steady intensification’ of the campaign, while denying that ‘regime change’ was UK policy. The US and the UK have already disagreed over whether it would be legitimate to target Gaddafi himself. The longer the stalemate persists, the less credibility the policy will have. The immediate options are limited. Either NATO accepts mediation by, say, the African Union and the world accepts partition with Gaddafi staying in power; or we escalate to remove Gaddafi and risk breaking the international consensus around UNSCR 1973 on Libya; or we carry on with the conflict indefinitely.

Many at Westminster argue that this situation underlines a lack of strategic thinking behind foreign and defence policy. As a result of last October’s Strategic Defence and Security Review (SDSR), the UK lacks an aircraft carrier, which – as First Sea Lord Admiral Sir Mark Stanhope has made clear – would have been deployed in Libya. UK operations off the Libyan coast have had to rely on ships which were due to be decommissioned, on long range bombers to conduct close air support and on a US spy plane for protection because the UK has scrapped its airborne maritime reconnaissance capability.

Last October, the Coalition’s National Security Strategy (NSS) sought to lay out the threats faced and to explain how government would respond to them. But the thinking behind it bore the hallmarks of the static mentality of the Cold War: the world of ‘known knowns’ – or at least ‘known unknowns’ – rather than the increasingly frightening world of ‘unknown unknowns’ we now live in.

We are living through a period of unprecedented instability, fuelled by over-population, competition for resources, resurgent Islamism, nationalism and extremism. But Whitehall is still set up to deal with the world as we would like it to be, not as it truly is. The Prime Minister established the new National Security Council (NSC) to overcome past shortcomings. However, he has failed to endow it with the means of being truly effective. It lacks a back office: its staff should be doing the thinking and producing a constant stream of strategic analysis and assessments. In the early days of Libya and the wider ‘Arab Spring’, the NSC was largely bypassed with the UK’s responses left to the Foreign Office.

Last year, the Commons Public Administration Select Committee, which I chair, called for a national strategy and trained strategic thinkers to support the NSC, but ministers just pointed to the Coalition Agreement as the nation’s foundation strategic document. How can Whitehall respond diplomatically and militarily to events, as in North Africa, if ministers and senior officials have to do all their own thinking on the hoof?

Mr Cameron looks comfortable fulfilling the UK’s global role. The UK is one of the few countries that can muster decisive global action in a crisis, drawing on historical experience and influence for the benefit of our national interests and for global stability. But is Whitehall geared to deal with all the challenges?

Mr Cameron must follow through the logic of his own instinct. Where he wills the ends, he must will the means. Whitehall needs more thinking power: more skilled and trained people who can consider the opportunities as well as the threats, and who are able to press ministers with alternative ideas and uncomfortable truths so that we stay ahead of the curve of events. Instead, we are forced to get involved in situations such as Libya before thinking through the consequences. Indeed, the government has yet to explain how the conflict there will conclude.