On 24 March 1999, NATO began air strikes on the Federal Republic of Yugoslavia. Known as Operation ‘Allied Force’, it was the alliance’s second combat operation in the Balkans in just four years. As NATO’s official historian I had travelled all over the region with the first mission, and on leaving my base in Sarajevo in the summer of 1997, shared my belief with colleagues that Serbian aggression was not yet done, and we would soon be back. I was right, and, within two years, in response to President Slobodan Milošević’s orders for ethnic cleansing to be carried out in Kosovo, NATO leaders agreed to a two-day air strike, convinced that the Serbian president would cave in, as he had done before.

When Milošević ignored the subsequent alliance air campaign, it gradually escalated into a 78-day operation. Then, on 3 June 1999 Milošević finally surrendered to NATO’s demands. Afterwards, airpower-advocates came out of the woodwork, claiming that Operation ‘Allied Force’ had fulfilled the prophecies of Giulio Douhet (1869-1930), Italian father of airpower doctrine, that skyborne operations alone were capable of breaking a nation’s will to fight. Douhet had first argued this in his seminal volume, Command of the Air (1921), and the turn of events in Kosovo seemed to reiterate the efficacy of air alone in deciding strategic outcomes.

Such claims were not new. They were embraced by Britain’s Hugh Trenchard and the American Billy Mitchell in the inter-war era, and were periodically advanced during the Second World War by bomber barons including Hermann Göring, Arthur Harris, Curtis Le May, Carl Spaatz, Ira Eaker, and Hap Arnold. Later experiences during the Gulf Wars of 1991 and 2003, and after the Bosnian air campaign, in Operation ‘Deliberate Force’ of 1995, and the intervention in Libya of March-October 2011, Operation ‘Unified Protector’, reinforced this argument. After Milošević’s capitulation in 1999, the doyen of military historians, John Keegan (1934-2012), felt moved to write a newspaper article, which concluded:

There are certain dates in the history of warfare that mark real turning points. 20 November 1917 is one, when at Cambrai the tank showed that the traditional dominance of infantry, cavalry and artillery on the battlefield had been overthrown. 11 November 1940 is another when the sinking of the Italian fleet at Taranto demonstrated that the aircraft carrier and its aircraft had abolished the age-old supremacy of the battleship. Now there is a new date to fix on the calendar: 3 June 1999, when the capitulation of President Milošević proved that a war can be won by airpower alone… The doubters are wrong. This was a victory through air power. I didn’t want to change my beliefs, but there is too much evidence accumulating to stick to the article of faith. It now does look as if air power has prevailed in the Balkans, and that the time has come to redefine how victory in war may be won.

Disciples of airpower rose to applaud. Some had vested interests in manufacturing airborne platforms, others wore air force uniforms, but even President Clinton weighed in with the observation that ‘a sustained air campaign, under the right conditions, can stop an army on the ground’. Keegan’s words in particular caused huge debate at the turn of the Millenium. I remember thinking at the time, again as one who was there, with knowledge of that tortuous Balkan terrain, ‘Keegan is wrong’. My own assessment was that airpower had not advanced diplomacy, had failed to halt ethnic cleansing in the region (the reason for NATO’s presence in the first place), and that it was the threat of ground-force intervention, led by that wise old warrior General Sir Mike Jackson, that caused the Serbians to cave in, not airpower alone.

By contrast, a much-quoted extract of a 1994 history of the Korean War by the American military scholar T.R. Fehrenbach (1925-2013) was doing the rounds at the same time: ‘You may fly over a land forever; you may bomb it, atomize it, and wipe it clean of life – but if you desire to defend it, protect it, and keep it for civilization, you must do this on the ground, the way the Roman Legions did – by putting your soldiers in the mud.’

As we subsequently absorbed the additional fighting domains of space, information and cyber, the debate moved on to accept that airpower, though a vitally important component of modern operations, could not prevail on its own. It was a lesson first apparent at the Battle of Amiens, on 8 August 1918, when the then principal assets of infantry, engineers, armour, artillery and air shared the victor’s laurels in what became known as the ‘Black Day of the German Army’. When war historians seek to understand deep historical trends, one factor rises to prominence repeatedly. The siren lure of technology. Time after time, a new development, whether gunpowder, rifled weapons, steam, the machine-gun, dreadnoughts, submarines, aircraft carriers, gas, tanks, or aircraft, offer politicians a cheaper way to maintain their armed forces and fight wars, exposing fewer lives to slaughter. And it never works. Reliance on one arm to prevail brings a ‘Maginot Line’ mentality and invariably leads to disaster, whereas we now know the ‘golfbag’ approach to war, having many different options at hand, if expensive, has often proved to be the winning formula.

And so we find the world has come full circle. Despite the Israel Defence Forces (IDF) being obliged to fight its controversial battles in Gaza by air and by land, its ongoing campaign over the skies of Iran, Operation Rising Lion, is alleged to be a supreme success story. There is talk of Iran’s defeat and regime change achieved solely by the IDF’s deft use of drones, its aging fleet of 320 F-15 and F-16 fighters, and new squadrons of 36 F-35-I stealth strike aircraft, given extended range by KC-707 and newer KC-46 and air-to-air refuelling tankers, and directed by its five EL/W-2085 airborne early warning and control machines. Journalists and commentators who should know better are asserting that it is air and air alone which has achieved this stunning humbling of Iran.

Many top Islamic Revolutionary Guard Corps (IRGC) air force and army commanders, the modern equivalent of the Waffen-SS in the Ayatollah’s regime, have been assassinated by drone or smart munitions, with their immediate replacements also targeted. Damage was reported to the Kermanshah underground holding facility in the Zagros Mountains, near the Iraqi border, where the IRGC Aerospace Force store and launch their ballistic missiles. Other attacks include on the Tabriz air base, home to three squadrons of the Iranian Air Force’s MiG-29s and F-5s. Known in the trade as SEAD (Suppression of Enemy Air Defence), fully two thirds of Iran’s protective systems of tracked and wheeled gun, surface to air missile, and radar devices, around 120 units, appear to have been taken out, and the IRGC-controlled rocket batteries are firing fewer, more poorly aimed munitions at Israel in return. Israeli pilots boast of being able to cruise over Tehran with minimal interference. Perhaps the tipping point came with the regime’s underground nuclear facilities being targeted by American bombers on 22 June.

This does not, however, amount to a campaign solely pursued by air. Drones were videoed being assembled by detachments of Israeli special forces at secret bases inside Iran, while strikes against many individuals and headquarters will have been laser target-marked beforehand by Israeli commandos and agents operating on the ground. As I found, sitting in military headquarters during the 2003 Gulf War, the key to success is swift and effective Battle Damage Assessment (BDA), which negates the need for multiple hits on the same target and is achieved through both Physical Damage Assessment (PDA) and Functional Damage Assessment (FDA). Although satellite imagery plays a role, this will be best achieved through Israeli-American reconnaissance and surveillance by trained eyes on the ground. Thus, even in fast-paced ultra-modern war, reliance on airpower has a vital land element.

The debate of recent days has swung to focus on Iran’s three principal uranium enrichment facilities at Isfahan and Natanz, and another at Fordow. Isfahan, in central Iran, is home to the country’s largest nuclear research complex. It employs 3,000 scientists and is suspected of being the centre of Iran’s nuclear programme. Natanz is 40-50 yards beneath the surface in subterranean tunnels, while Fordow is an estimated 100 yards down, both located in lonely mountainous regions south of Tehran. This trio of plants have long been known to Western governments and the International Atomic Energy Authority (IAEA). It is the very secrecy of their location and concealment deep in the hills, plus their protected underground ceilings of up to eight yards of reinforced, hardened concrete that is giving Israel, the IAEA and America most cause for concern. I remember from my nearly 20 years lecturing at the UK Defence Academy, our concrete expert (yes, we had one) revealing that the world’s leading developers of bomb-proof-grade concrete were – yes, you’ve guessed it, the Iranians. Think Albert Speer or James Bond’s adversaries and you have the picture.

While the surface buildings and access points have been destroyed or damaged, it appears the IDF did not have the munitions to finish these off. Enter the American GBU-57 MOP (Massive Ordnance Penetrator) precision-guided ‘bunker buster’ bomb, of the kind used in the early hours of 22 June. New-found war experts are savouring every detail of its 20.5-foot length, 30,000-pound weight, and alleged ability to penetrate down to 60 yards. The only US aircraft capable of carrying a pair of these monsters is the B-2 Spirit bomber, mostly based at Whiteman Air Force Base, Missouri. Their strike on Iran was enabled by over 30 USAF KC-135R and KC-46A refuelling tankers, which open-source civilian analysts and plane-spotters picked up arcing eastwards into Atlantic skies, to enable long-range, missions to Iran, a 7,000-mile round trip. Given that these are the key enablers of American and British air power (a ‘centre of gravity’), the recent attacks on two RAF Voyager tankers at their Brize Norton base in Oxfordshire and alleged spying on RAF Akrotiri, Cyprus, are also matters for grave concern. The attack at Brize with paint by pro-Palestinian militants could so easily have been with explosives by pro-Russian agents. Air assets, except those on carriers, are ultimately vulnerable to activity on the ground.

Best estimates suggest the US Air Force commissioned the manufacture of only 20 MPOs, of which six were reportedly used in the 22 June mission. They are rather like the upper scale of Barnes Wallis’ special-purpose munitions ranging from ‘Upkeep’ bouncing bombs and 12,000-pound ‘Tallboys’ to 22,000-pound ‘Grand Slams,’ paired to the adapted 617 Squadron Lancaster bombers of old.

Print and broadcast media have been full of discussions of the B-2 missions to destroy Natanz and Fordow without doing the basic maths to conclude that GBU-57s were barely able to penetrate to the tunnels at Natanz, let alone those at Fordow, and with no attention taken of the facilities’ eight-yard protective concrete ceilings, hence multiple munitions being used. Around 30 US Tomahawk cruise missiles launched from the submarine USS Georgia, cruising in the Gulf region, were also used. But there’s more. Satellite imagery picked up trucks removing equipment beforehand from both areas, which may include some enriched material. Given that the trigger for Israel’s kinetic action in this lightning war was the destruction of Iran’s nuclear capabilities, I would not wish to pack up and return home for tea and medals without ascertaining in person that these facilities, their delicate equipment, and associated uranium, have been put beyond use – forever. That requires ground-based Battle Damage Assessment by special forces or trained observers.

The United States and Israel have pursued a very proactive, high-risk air campaign, precisely to avoid inserting large numbers of ground forces into Iran, whose population of 92 million vastly outnumbers that of Israel’s 10 million. Yet, there can never be victory by sky war alone. This is a vital stratagem Benjamin Netanyahu and Donald Trump, in their haste to hit Iran at its weakest, appear to have overlooked. The currently damaged state of Iran’s underground centrifuges and other nuclear equipment mirrors the fragile government in Tehran. The Ayatollah regime is down, but not yet out. Normally, it might call for asymmetric campaigns against Israel, America, maybe against other states too (hence prime minister Starmer being at pains to stress the UK’s non-involvement), by its allied militias in the region, but they have been mostly degraded, almost to extinction, and scattered by Israel.

Iran will be reaching out to Russia, China and possibly North Korea for military assistance. All will support Tehran diplomatically, but Moscow has its hands more than full with Ukraine, Beijing is focused on Taiwan and dominating the wider Pacific, while Pyongyang’s current military adventurism in Ukraine has not gone well. It is now apparent that Israel and America jointly launched strikes on Iran to remove its nukes and effect regime change. A replacement leader, Reza Pahlavi, born in 1960, eldest son and legitimate heir of the last Shah, overthrown in 1979, is waiting in the wings, based in Egypt with a fully formed government-in-exile. He may have the loyalty of many Iranians, but they are disorganised, currently leaderless, and their country is still under the thumb of the Ayatollahs and the IRGC fanatics.

Yet, who will occupy Iran, how and when, even if only temporarily, to prevent the rise of another militant Shia republic, bent on Israel’s very destruction? Airpower cannot manage revolution or regime change. As in Libya, it can help trigger it, but not control or steer it. Postwar Germany, Japan, and latterly the Balkans, required substantial land-force components, which had to remain until democratic elections took place. British Forces in Germany had a life of 75 years from 1945-2020, while manpower-heavy peacekeeping missions between ‘frozen-conflict’ states such as Korea and Cyprus are ongoing.

An enormous military machine launching a major kinetic attack against a weaker neighbour in the early hours of 22 June, as the US did against Iran, has dangerous precedents. Nazi Germany’s Operation Barbarossa began against the USSR in 1941 on that same day, as did Russia’s counter-stroke, Operation Bagration, of 1944. Despite substantial air activity, both assaults were ultimately decided on the ground. The 22 June 2025 conventional munitions hit on a hostile power’s nuclear capabilities is a first for airpower. Yet, whatever you achieve from the air, as Fehrenbach reminded us, strategic success always requires boots on the ground, the way the Roman Legions did – by putting your soldiers in the mud.