The announcement last year of a security partnership ^[1] between Australia, the United Kingdom and the United States to procure nuclear submarines sent shockwaves across the Indo-Pacific. AUKUS promises to transform America’s force posture in the region and build the foundations of an integrated strategy to respond to China’s rise as a military power.

Yet from the outset AUKUS faced major criticism, not so much from China as from America’s oldest ally, France. Paris accused Washington of a ‘stab in the back’ ^[2] after Australia ‘blindsided’ France with the unceremonious termination of a $60 billion contract ^[3] with the French shipbuilder Naval Group to develop a fleet of diesel–electric submarines for the Royal Australian Navy. Since it was agreed in 2016, France had hailed the contract as a pillar of Paris’s defence engagement ^[4] and enduring security commitment to the Indo-Pacific. Today, that robust strategic posture is in tatters.

The loss of the contract and France’s overall exclusion from AUKUS demonstrated Europe’s increasingly marginal role in Asian security affairs. This is despite attempts by France ^[5] and Germany ^[6] to support freedom-of-navigation operations in defiance of China’s actions in the South China Sea. Were these manoeuvres not enough to convince Washington that the European Union offered a robust commitment to Asia?

A careful study of France’s strategic interests reveals that the republic could never become the fully integrated military ally the US desires in the Indo-Pacific. Historically, modern France was torn between continental and maritime security responsibilities. Despite its attempts to form an overseas empire to rival Britain (which failed), France’s core security interests remained in Europe—and particularly after two world wars with the perennial threat of Germany. That experience taught France that it can’t rely on the UK, let alone the US, to maintain its security. The seas acted as a natural barrier for the Anglo-Saxon states not available to the Gallic French.

In the 1960s, President Charles de Gaulle defined France’s uniquely autonomous relationship with the NATO alliance. According to the ‘Gaullist’ foreign policy, France withdrew from the joint military command structure of NATO and pursued its own nuclear deterrent independently from the UK and the US. That effectively allowed France to remain a core partner of NATO without committing any forces to the defence of the continent in the event it decided not to contest a determined Soviet breakthrough into West Germany. And in the event of Germany’s—or Britain’s—re-emergence as a significant security threat, France maintained its independent nuclear deterrent.

A strong Anglo-Saxon alliance with Britain and Australia is now emerging as part of Washington’s Indo-Pacific strategy. Frankly, that is precisely what the US requires to tackle the challenge posed by China at sea. The UK and Australia are both bound to the US by history, by military alliances and through the Five Eyes intelligence-sharing partnership, which also includes Canada and New Zealand. AUKUS therefore has the potential to become an integrated defence partnership in a manner impossible for the sovereigntist French or the larger European Union.

Certainly, France doesn’t lack significant interests in the region. It maintains French Polynesia, Wallis and Futuna, and the relatively large island of New Caledonia—home to France’s largest military station in the region—a status threatened by a contested independence referendum ^[7]. It also has a series of dependencies ^[8] in the Indian Ocean, most notably Mayotte and Reunion. There are some 1.6 million French citizens ^[9] residing across the Indo-Pacific protected by a complement of 7,000 forces and 12 naval vessels ^[8] permanently stationed in theatre. It has a larger presence in the region than the UK, which only maintains 1,000 Gurkhas in theatre in Brunei Darussalam.

What, then, is the appropriate level of Franco-American security cooperation in the Indo-Pacific? Given France’s historical autonomous security policy, the US can’t integrate its military forces to the same level as the Five Eyes nations, which are bound by agreements to promote seamless interoperability among their armed forces. What the US needs is an institution to include France as an emerging security partner to deter China, but one that respects strategic autonomy. Of course, it already has such a mechanism in the Quadrilateral Security Dialogue with India, Japan and Australia.

The idea of a ‘Quad-plus’ arrangement ^[10] isn’t new, and it has been specifically floated to include a more robust French presence in the region. But considering that France is itself an Indo-Pacific power—barring a series of independence referendums across all its possessions—there seems to be no real obstacle to fully integrating this discontented ally into the Quad. Paris has recognised the potential of the Quad nations for some time. There’s already a France–India–Australia ^[11] trilateral on maritime safety and a Japan–Australia–France trilateral on South Pacific affairs. This relationship is buttressed by profitable defence contracts, including a US$9.4 billion contract ^[12] to sell Rafale fighter jets to India, now mired in corruption allegations.

The real obstacle is Franco-Australian relations. While the damage to Franco-American relations has subsided, the damage to Franco-Australian relations ^[13] may persist for years to come—unless Canberra and Paris agree to mend their differences, an outcome both countries need. Even if offered, Paris may choose not to join the multilateral format of the Quad in defiance of Australia’s role. That would render both a Quad-plus and any existing trilateral forums ^[11] defunct. But without a larger institutional framework, a Franco-Indian declaration to ‘act jointly’ ^[14] in the region and France’s revitalised ties with Japan will only remain diplomatic posturing in response to AUKUS.

The solution is, as always, diplomacy. It will require the US to engage directly with the two allied nations to restore strong ties in support of its larger, shared strategic vision for the Indo-Pacific. That vision is clear: whereas the AUKUS nations are part of a singular, interoperable alliance command, the Quad-plus is a coalition that agrees to work jointly with the US to deter the shared challenge of China, but that ultimately retain varying levels of strategic autonomy.

While ‘the Quintuplet’ may not be the most attractive name for such an organisation, it is effectively what the US should form in order to reconcile and find an appropriate level of strategic cooperation with France. The Quad offers France everything it desires—a relevant military role tempered by its Gaullist autonomist traditions. That may not make up for a lost contract, but it will institutionalise security cooperation with France in a manner most conducive to the defence of the Indo-Pacific.