Israel and Iran on the brink: Preventing the next war

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The 12-daywar of June 2025 marks a watershed moment: Israel, Iran and the United States demonstrated unprecedented willingness to engage in direct military confrontation. After Israel's large-scalestrikes inside Iran on 13 June broke the taboo, the two sides appear to be bracing for further conflict. For over 20 years, European actors have sought to avert a conflict with Iran that could further destabilise a war-tornregion close to its borders, triggering migration flows, terrorism and threats to energy supplies. This Brief examines the impact of the 12-daywar, what to expect next, and how Europe can help prevent a broader regional conflagration.

Taking stock of the 12-day war

Several factors emboldened Israel. Tehran's backing of anti-Israelarmed groups and hostile rhetoric led Israel to perceive Iran's nuclear programme as an existential threat. Yet Israel held back for decades. However, after the Hamas terrorist attacks of 7 October 2023, Benjamin Netanyahu adopted a more aggressive 'mow the grass' strategy across the region. Over the past year, this militarised approach has undermined two decades of Iranian deterrence against an Israeli strike. This, combined with Donald Trump's return to power and the erosion of US checks and balances, gave Israel a unique opportunity to launch a war long resisted by previous US presidents.

The region is still absorbing the impact of the war. Israeli jets, refuelled by the US, bombed targets across Iran, including nuclear, military and energy sites. Iran responded with unprecedented missile salvos, breaching Israel's advanced defence systems and hitting military sites and the Haifa oil refinery⁽¹⁾. The war became a race: which would run out first - Iran's missiles, or Israeli and US anti-missileinterceptors?

After the ceasefire, Iranian officials projected confidence⁽²⁾. They claimed that Iran had resisted Trump's call for unconditional surrender, inflicted significant damage on Israel and forced Israel to halt strikes as Trump sought to avoid a prolonged conflict⁽³⁾. Iran remains the only state actor to have directly struck Israel (despite bombings in Lebanon, Syria, Gaza, Yemen and most recently Qatar). Tehran's caution in deploying Hezbollah and the Houthis also suggests preparation for a war of attrition. This may explain why over the 12 days, Iran reduced the number of its missile attacks, focusing on precision, and refrained from mobilising regional armed groups.

After the US strike on its nuclear facilities, Iran hit the Al Udeid base in Qatar to signal that continued war would impose costs on Washington and its Arab allies. Until then, Gulf Cooperation Council (GCC) states kept their airspace and shipping routes open, and managed to stay out of the fighting to protect their economies. Yet Iran's attack on a historically friendly Arab state signalled that escalation could draw in the entire region. Across the Middle East, many fear that renewed strikes could drag a reluctant Trump into a conflict that could be far more destructive in the next round.

The regional deterrence equation

Following the 2003 US invasion of Iraq, regional rivalry centred on Israel and Iran. After the fall of Saddam Hussein, Iran emerged as Israel's main military counterweight, underpinned by three core assets: a massive missile arsenal; a coalition of loyal armed groups (including Hezbollah, Hamas, Iraqi resistance factions, and the Houthis); and nuclear advances nearing weapons-gradelevels. Israel, meanwhile, enjoys unmatched military superiority in the Middle East, with near-unconditionalUS backing, superior intelligence and state-of-the-artairdefences.

Over the past year, the deterrence equation that dissuaded Israel from striking Iran broke down, with Israel significantly weakening Iran's so-called'axis of resistance'. The June US and Israeli bombings severely damaged Iranian nuclear facilities, temporarily halting uranium enrichment⁽⁴⁾. Yet Iran's intentions remain opaque. It has also curtailed International Atomic Energy Agency (IAEA) monitoring activities, heightening global uncertainty.

Despite its still potent missile capabilities, Iran failed to defend its territory and nuclear assets, while suffering key intelligence losses - with over 30 senior military and security officials and 11 nuclear scientists reportedly assassinated⁽⁵⁾.

Israel's ability to penetrate deep into Iranian airspace - despite its size and defences - demonstrated a level of military reach previously unseen. For Saudi Arabia, Qatar and Turkey, this was a moment of reckoning: if Israel can do this in Iran, it can project similar force elsewhere.

Equally alarming was the 'Bibi effect' over Trump. Prior to June, Gulf and Turkish leaders had secured US support for lifting sanctions on Syria. Netanyahu's ability to pressure Trump into bombing Iran, and Israel's continual bombing in Syria, was jarring for regional leaders. This was exacerbated by Israel's unprecedented bombing of Qatar in September - which failed in its stated aim of killing Hamas negotiators. This strike - by one US ally against another - has deeply rattled the Gulf monarchies who can no longer depend on the US security umbrella to shield them from either Israelor Iran.

It is unclear if the US will pursue negotiations with Iran - or if it seeks total capitulation.

Equally troubling is uncertainty about Israel's endgame with Iran. Israel's shift from targeting Iran's nuclear programme to undermining state stability threatens regional security. GCC states worry that a fragmented Iran could derail economic plans for regional connectivity. Turkey, sharing a border with Iran (which hosts a population of over 90 million) and wary of Kurdish insurgents, fears the collapse of Iran's central authority.

In response to the 12-daywar and the Qatari strikes, regional actors are hedging and attempting to rebuild their own deterrence. GCC states are looking to diversify their defence partnerships beyond the US (including with Pakistan, Turkey and Egypt). In parallel, the Gulf monarchies hope that keeping both Tehran and Trump close will reduce the risk of being caught in the line of fire.

A fragile pause

The 12-daywar ended with an informal pause that nearly collapsed prior to Trump's last-minuteintervention. No formal ceasefire exists between Israel and Iran (unlike the fragile truce with Lebanon struck in November 2024). With no external guarantor or de-escalationhotline, the risk of renewed tensions from missteps by any party remains high.

Israel cannot sustain a prolonged war against Iran without active US military support⁽⁶⁾. Iran's near-termstrategy combines back-channeldiplomacy to dissuade Trump from supporting future Israeli strikes with military deterrence, rebuilding its air defences and missile stockpiles with Russian and Chinese support.

Iran faces an uphill battle. It is unclear how quickly it can rebuild its conventional military deterrence, how far China and Russia will aid this effort and whether Israel might strike again first. Moreover, it is unclear if the US will pursue negotiations with Iran - or if it seeks total capitulation. Trump, claiming to have 'obliterated' Iran's nuclear programme, appears uninterested in a deal and perceives no urgent threat.

Despite an obvious tactical win, the strategic success of the US and Israeli strikes against Iran's nuclear threat is at best uncertain, and at worst could have major blowback. The costly war failed to bring Iran and the US closer to a deal. Israel and Iran respectively reported 28 and over 1 000 dead as a result of the conflict, with thousands losing their homes. American and Israeli operations came with a significant financial cost, and depleted US stockpiles - including an estimated quarter of American high-endmissile interceptors⁽⁷⁾. Yet the deadlock over Iran's ability to enrich uraniumpersists.

In the absence of a viable diplomatic path and with renewed war a likely prospect, Iran might covertly pursue nuclear weapons at undeclared sites. The fate of its 400 kg of highly enriched uranium - enough to manufacture several nuclear bombs - remains unknown. With IAEA monitoring now highly restricted, Europe may end up relying on increasingly politicised US or Israeli intelligence.

Finally, this dynamic locks Israel, the US and possibly Europe into a perpetual confrontation with Iran, marked by recurring military strikes to thwart its nuclear and missiles advancements. While Iran is seemingly using this stockpile as a chip to bargain with the US, Israel could use it as a justification to resume military strikes, arguing that low-coststrikes can stall Iran's nuclear ambitions. While Trump appears eager to end hostilities, the 12-daywar and Qatar strikes suggest that pressure from Netanyahu could drag him into renewedconflict.

The case for European diplomacy

The EU/E3-ledframework for nuclear talks with Tehran, launched shortly after the US invasion of Iraq, sought to prevent a new war in the Middle East. It resulted in the historic 2015 nuclear deal, which capped Iran's nuclear programme at civilian needs and was fully implemented, even for a year after the Trump administration withdrew from it in 2018. Meanwhile, European diplomacy forestalled looming Israeli and US military action against Iran - until June.

The military option clearly has limitations and comes with a high price tag. Estimates suggest the June attacks set back Iran's nuclear programme by only a year or two⁽⁸⁾. In contrast, the 2015 nuclear deal achieved a similar delay without a single shot fired. Without a diplomatic breakthrough, Israel is likely to resume its strikes inside Iran - starting alone but ultimately relying on US support in both defensive and offensive operations.

A future war would likely escalate, with Iran stepping up attacks on US forces in the GCC and Iraq. It could also jeopardise global energy supplies through vulnerable routes like the Red Sea and Strait of Hormuz, targeted by Iran and its Houthi allies. By contrast, a negotiated deal could roll back Iran's programme - without the risks of a broader regional war.

Following the 12 day-war, the E3 countries triggered the snapback process, reimposing all UN and EU sanctions on Iran. They gambled that time pressure and heightened risk of war would force Tehran to grant inspectors access and verify the fate of its uranium stockpile. But Iran refused to cede its last remaining bargaining chips in a potential future negotiation with the US, in return for an extension of snapback - a tool that is largely viewed as a European gun toits head.

Having exhausted its snapback leverage, the E3 should now look to provide a soft landing to avoid fuelling an escalatory dynamic with Iran. The immediate priority should be to go back to the diplomatic drawing board. This effort should be broadened beyond the E3: the EU, Switzerland and Norway should accelerate shuttle diplomacy between Iran, Israel and the White House. While a comprehensive deal is unlikely at this stage, a series of small reciprocal steps could address concerns on all sides and limit the risks of escalation.

This could start with mutual restraint: for example, the West refraining from enforcing oil restrictions on shipments to China, in return for Iran continuing to halt enrichment. This would give Trump a political win on his 'zero enrichment' demand at little cost, since enrichment has practically stalled due to the strikes. Iran could frame the pause as temporary while it repairs the damage to its nuclear facilities and consistent with its perceived right to enrichment. This process should then encourage Iran to continue its engagement with international inspectors under the Non-ProliferationTreaty, including by providing access to bombed nuclear sites.

Crucially, the US and Europe must also restrain Israel from attacking Iran while enrichment is paused and future talks are pursued.

Finally, Europe should deepen its cooperation with GCC partners, as avoiding or containing a renewed Israel-Iranwar is a shared priority. A new 'E3/EU-G3-GCC', platform with Qatar, Saudi Arabia and the United Arab Emirates (UAE) could lead regional de-escalationefforts. Given the interlinkages between the Gaza crisis, the Iran dossier, and stability in the Levant region, this would provide Europeans with a much stronger basis on which to pursue comprehensive security in the Middle East.

References

• 1'Through trial and error, Iran found gaps in Israel's storied air defenses', The Wall Street Journal, 15 July 2025. See also: 'Lessons observed from the war between Israel and Iran', War on the Rocks, 16 July 2025.
• 2'Iran's Ayatollah Khamenei claims victory over Israel, "a big slap in the face" to the U.S.', CBS News, 26 June 2025.
• 3'The consequences of Iran's attacks in the 12 day war. What did Israel censor?', Euronews (in Parsi), 6 August 2025.
• 4'Iran will not give up nuclear enrichment, top official confirms in exclusive Fox News interview', Fox News, 16 July 2025.
• 5'Israel killed 30 Iranian security chiefs and 11 nuclear scientists, Israeli official says', Reuters, 27 June 2025.
• 6Eilam, E., 'Why Israel and Iran had decided to avoid a long war', Royal United Services Institute, 7 July 2025.
• 7'US used about a quarter of its high-end missile interceptors in Israel-Iran war, exposing supply gap', CNN, 31 July 2025.
• 8'Pentagon says US strikes set back Iran nuclear program "one to two years"', The Guardian, 2 July 2025.

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