Executive Summary Europe faces a growing convergence of Russian and Iranian air and missile threats, driven by both technological cooperation and parallel strategic behavior. Recent developments—including long-range Iranian missile launches and sustained Russian aerial attacks in Ukraine—have reinforced the perception that the European continent is increasingly exposed to high-intensity airborne threats. While NATO’s ballistic missile defense architecture provides some protection, it remains limited in scope and heavily dependent on US capabilities. Europe lacks effective defenses against certain categories of Russian missiles and cannot assume that existing protection against Iranian systems will remain fully reliable over time. In this context, nuclear deterrence remains the ultimate layer of European security. At the same time, risks such as potential Iranian nuclear weaponization and renewed proliferation dynamics could further destabilize the strategic environment. Amid growing uncertainty regarding US commitments, European countries are exploring additional forms of reassurance, including enhanced Franco-British cooperation. Whether Europe can sustain the necessary investments in defense and deterrence remains an open question. *** On March 20, 2026, Tehran reportedly fired two long-range ballistic missiles in the direction of Diego Garcia, nearly 4,000 kilometers from Iranian territory. This unexpected event confirmed that a large part of the European continent could now be targeted by Iranian missiles. This came on the heels of several Iranian ballistic missile launches toward Türkiye. These incidents happened in the context of a growing perception of airborne threats in Europe. For more than four years now, European citizens have seen waves of sometimes massive aerial attacks – ballistic missiles, cruise missiles and drones – by Russia against Ukraine, and by Iran against cities, economic infrastructure and military installations in Israel and the Gulf countries. This is changing perceptions of the strategic threats the continent is likely to face in the coming years. Specifically, Europe will need to address two interconnected strategic challenges: Iran and Russia. They are linked to one another in many ways. While rivals in the Caucasus – and not formally allies – Tehran and Moscow have consistently assisted each other in many military (and civilian nuclear) fields, notably air defense and, more recently, drone technology. After selling drones to Moscow starting in 2022, the Islamic Republic transferred drone technology to Russia for joint or licensed production in Alabuga (Tatarstan). Historically, European missile defense was geared towards Iran due to the Islamic Republic’s hostility towards the West, its vast and diverse ballistic missile program and military-related nuclear activities. The NATO Ballistic Missile Defense (BMD) achieved initial capability in 2016 and was enhanced over the years. Although it integrates various national capabilities, its main component is the US “European Phased Adaptive Approach”, completed in 2024 and which includes a radar in Türkiye and Aegis interceptors in Poland, Romania, and the Mediterranean. National contributions also include short-range interception capabilities (notably the US Patriot-3 and French-Italian SAMP/T). Since the beginning of the US-Israeli attack on Iran, the NATO BMD system has intercepted four missiles launched toward Türkiye. The war also raises questions regarding the possible targeting of non-NATO countries, such as Cyprus, which was targeted by Iranian drones in early March. Like all EU members, Cyprus is covered by Article 42.7 of the Lisbon Treaty, which commits Europeans to assist each other in the event of an armed attack. French President Emmanuel Macron confirmed that “when Cyprus is attacked, it is Europe that is attacked”. There is no doubt that the current war in the Middle East will confirm the need for Europe to continue investing in air and missile defense, especially given the uncertainties about the future of US protection. The problem Europeans face is twofold: First, they have no protection against intermediate-range Russian ballistic missiles. The NATO Ballistic Missile Defense system cannot easily be reoriented toward the East. Additional radars and US interceptors would have to be deployed. A limited capability will be provided by Israeli Arrow-3 systems purchased by Germany, which are capable of exo-atmospheric interception. Second, they cannot even take for granted that the protection against long-range Iranian ballistic missiles will be available in the long run, given how much it relies on US Aegis Ashore systems. Hence the importance of nuclear deterrence, the second – and final – layer of Europe’s protection against major strategic threats. Nuclear deterrence is not only geared towards the protection of national territories against nuclear strikes, although this is often considered its primary mission. It is widely acknowledged that an adversary should think twice before resorting to massive conventional air attacks against a territory covered by nuclear protection. But the primary role of nuclear weapons in Europe is and will remain to protect the continent against nuclear attacks or counter nuclear blackmail. Since 2022, on multiple occasions, Russia has played the nuclear card to intimidate Ukraine and the West. This has proven fruitful in discouraging direct military assistance to Kyiv. But Europe is concerned by the risk of actual Russian nuclear use. This could happen in the course of the Ukraine war or of a future confrontation with Europe, should the Russian armed forces face defeat. Furthermore, if the Islamic Republic of Iran (or any successor regime) was to resume weaponization and achieve operational nuclear capability – something that might be achieved in a matter of months rather than years – then the global nuclear landscape would be transformed. Not only would it see the first new nuclear-armed State in twenty years, but it could witness a new wave of nuclear proliferation. A first reason is that it would imply a de jure or at least de facto withdrawal from the Nuclear Non-Proliferation Treaty (NPT), forming a probably deadly breach in the global norm created by the 1968 treaty. Iran would be the second country to withdraw from it after North Korea (notwithstanding the legally dubious way it withdrew from it in 2003). Countries such as Japan or South Korea, but also maybe Ukraine, which can testify to the limits of US protection or assistance, would then be certainly tempted to embark on national nuclear programs, for the normative barrier against proliferation would then have been dangerously lowered. The second reason why an Iranian bomb would create a new proliferation dynamic is a regional cascade. Saudi Arabia is on record to say that it could not remain idle. This could force Israel to make public its widely suspected nuclear capability, which in turn would pressure Egypt to go along the same path as Saudi Arabia. The new dynamics of regional proliferation could then reach Algeria (which had suspicious nuclear activities in the early 1990s). Today Europe relies on the three allied nuclear powers – the United States, the United Kingdom, and France – for its nuclear protection. US and UK nuclear weapons are available for common NATO planning, including through the procedure known as nuclear sharing, whereby several European air forces can carry US nuclear bombs (which remain under US control). To this day, the Trump administration maintains that this mechanism will remain untouched. But the growing uncertainties regarding the future of US protection to the continent have led Paris, and to some extent London, to hedge against a possible failure or withdrawal of the US nuclear umbrella. At this point in time, there is no intention nor any plan for France (even less for the United Kingdom) to replace the US nuclear protection to Europe. But what Paris and London have set up in the past twelve months can be described as “nuclear reassurance” measures that could one day form the basis of a European deterrent. First, Paris and London considerably reinforced their nuclear cooperation through the Northwood Declaration of July 10, 2025. The Declaration stated that “there is no extreme threat to Europe that would not prompt a response by our two nations” and that their nuclear forces could be “coordinated”. Second, France announced on March 2, 2026 that it proposed a concept of “Forward Deterrence” to better ensure reassurance and protection of the continent. Based on bilateral arrangements with interested countries, this could include the deployment of “elements of strategic forces” on allied territories. This would complicate adversary planning and increase survivability of French Strategic Air Forces. Conversely, allies are expected to contribute to strategic early warning and air or missile defense. Emmanuel Macron’s speech was essentially and understandably devoted to the Russian nuclear threat, but the French president made it clear that the nation’s nuclear deterrent was meant to protect Europe against any country threat against vital interests. For the first time since the end of the Cold War, the European nuclear landscape is in flux, in a global nuclear context characterized by “nuclear nationalism”, increasing arsenals, the disappearance of the bilateral US-Russian arms control framework, and renewed fears of proliferation. However, in a fiscally constrained environment, it remains to be seen whether Europe will have the ability to spend more on power projection, air and missile defense, and nuclear arsenals. « Europe rallies around Cyprus after Iranian drone hits island », PBS, 9 March 2026, https://www.pbs.org/newshour/world/europe-rallies-around-cyprus-after-iranian-drone-hits-island For the scope of this paper, « long-range » Iranian missiles and « intermediate-range » Russian missiles refer to less than missiles with a maximum range of less than 5000 km. In the Fall of 2022, US intelligence was concerned that Russia would use nuclear weapons if the Ukrainian Armed Forces breached the Kherson line and recaptured Crimea. Statement by the United Kingdom and the French Republic on Nuclear Policy and Coordination – July 2025, https://www.gov.uk/government/news/northwood-declaration-10-july-2025-uk-france-joint-nuclear-statement Speech by the President of the Republic on France’s nuclear deterrence, 2 March 2026, https://www.elysee.fr/en/emmanuel-macron/2026/03/02/visit-to-the-ile-longue-operational-base