Sarah Ingham is author of The Military Covenant: its impact on civil-military relations in Britain.

Si vis pacem, para bellum. If you want peace, prepare for war. Or, as they’ve been saying in the Kremlin over the past few years: si vis bellum, para bellum.

The invasion of Ukraine has confirmed the seasoned military cliché that no plan survives first contact with the enemy. Russia has suffered tactical defeats and losses of up to 15,000 personnel, including senior commanders.

But Moscow’s war-chest stockpile of $630 billion, combined with its massive investment in defence, and its recent economic pivot to China, suggests that Mad Vlad is perhaps not quite as strategically irrational as some want to believe.

The Ukrainians’ fight for their country’s survival in now in its third month. They have won a massive moral victory by beating back the Russian advance on their capital, Kyiv.

But more than a quarter of Ukraine’s population of 44 million is now displaced, with five million fleeing the country. Areas have been bombarded to rubble. Evidence is being compiled that the Russians have committed war crimes, including in Bucha, on a scale not seen in Europe since Srebrenica in 1995.

Meanwhile, NATO has 3.3 million active military personnel – doing precious little. The organisation, however, is having a good war. The 69-year-old Putin’s attempts to hold back the years with the Botox syringe has nothing on the sudden spring in the step of the rejuvenated 73-year-old NATO. It’s relevant again.

The UK and US were among the 12 which signed the North Atlantic Treaty in early 1949, shortly after the start of the Cold War. A defensive alliance, NATO’s Article V states that an attack on one member is an attack on all.

Although the organisation embodies the precept of collective security, inevitably national self-interest is never far away. Its founding father, Ernest Bevin, would have agreed that, for Britain, NATO’s initial objective was “to keep the Russians out, the Americans in and the Germans down”.

Until the fall of the Berlin Wall in 1989, symbolising the beginning of the end of the Soviet empire, NATO endured without firing a shot. By then, the 12 were 16.

In a half century of nuclear Mutually Assured Destruction, wars and proxy wars such as Korea and Vietnam, NATO avoided direct conflict with its main adversary, the Warsaw Pact nations of the Soviet Union and its eastern European satellites.

With the final fracturing of communist empire in 1991, it must be asked why NATO did not congratulate itself on a job well done, pack up and go home. A year earlier, the late Alan Clark, one-time Minister for Defence Procurement, believed that the organisation had outlived its usefulness, describing it as a “bureaucracy in search of a pension”.

The conflict in Bosnia (1992-95) provided NATO with a timely rationale for its survival. In 1994, the alliance fired its first shot in anger, when US F-16 fighters downed four Bosnian Serb aircraft.

Generally, however, its forces sat impotently on the side-lines, constrained by the United Nations and internal divisions, doing almost nothing to halt death, destruction and ethnic cleansing.

NATO finally got to unleash its airpower in a nine-day campaign in September 1995. Operation Deliberate Force was proof of the utility of force. Within weeks, the Bosnian Serbs were at the negotiating table.

Article V was invoked for the first time in 2001 after 9/11. While the initial strikes against Afghanistan could be justified, what about the expanded mission (under the auspices of the International Security Assistance Force) agreed by NATO in 2004? After all, British troops were sent to Helmand with a brief which included eradicating opium farming.

Wary about NATO’s intervention in Kosovo in 1999, Clark might have pointed out that the intervention in Afghanistan after 2006 reflects a military bureaucracy which, like all bureaucracies, becomes primarily interested in its own survival and well-being. (So, too, the NHS.)

For a defensive alliance that says North Atlantic on the tin, NATO has certainly stretched its remit. Bagram airbase is a long way from its Brussels’ HQ. But for a NATO with too much time on its hands, as a US Senator once observed, “It’s either out of area or out of business.”

More than three decades after the end of the Cold War, hot war has once again returned to Europe. Consequently, Finland and Sweden might join the current 30-member organisation.

But while surely not deliberately self-serving, was NATO’s expansion since 1999 always strategically wise? Householders who want to live at ease with their neighbours don’t plant light-blocking leylandii – let alone military infrastructure – on their boundaries.

As Helsinki and Stockholm prepare to join, they will probably be reassured to know that last year, as Moscow was drawing up invasion plans, the Organisation launched a Sustainability Roadmap, “a step towards a greener NATO”, according to the Secretary General’s Annual Report 2021.

Not only did it deliver its first ever internal conference on LGBTQ+ perspectives in the workplace, but it undertook to apply a “gender lens” to all it does in the pursuit of “equitable peace and security”.

Equitable or otherwise, peace and security is in limited supply in Ukraine right now. In the wake of the invasion, the perennial debate within NATO about funding and the two per cent GDP minimum has been halted, as the allies work out what the hell to do next. (Although many members persist in fuelling the Russian combat effort by their reliance on Moscow’s oil and gas.)

Yesterday Ben Wallace echoed the Foreign Secretary’s demand that Russia must be ejected from the whole of Ukraine, including territory annexed in 2014.

Is this proposed escalation political grandstanding? Or is it now formally collective NATO policy? After all, in the first Crimean War (1853-56), Britain acted in alliance with France, the Ottoman Turks and Sardinians – almost a proto-NATO – to drive Russia from the peninsula.

Should Britain and NATO now emulate Russia and be actively preparing for war? Or are more than three million armed personnel going to continue to sit it out while the Ukrainians battle it out?