Iran’s diplomatic and coercive channels and the credibility of its commitments, June–September 2026
ABSTRACT
This piece examines Iranian crisis decision-making between June and September 2026 under Mojtaba Khamenei, appointed Supreme Leader in March 2026. It asks which institutions carried Iran’s offers and its escalation, and how their divergence affected the credibility of Iranian commitments, matching open-source statements and actions by date, actor and channel. In September the Foreign Ministry passed offers through mediators while the Islamic Revolutionary Guard Corps (IRGC) continued missile and tanker attacks and the chief negotiator declared the era of “proportionate responses” over. The sources reviewed contain no crisis decision attributed to the Supreme Leader for this period. The arbiter able to bind both channels is invisible, which leaves Iran’s commitments unreadable to its counterparts.
1. Two channels and an absent arbiter
Iran is fighting the war that began with the US and Israeli strikes of 28 February 2026 under a new Supreme Leader. Janes (2026) read the March appointment of Mojtaba Khamenei as a continuity choice, grounded in his IRGC and intelligence ties, and as a sign that elite cohesion would hold in the immediate term. By September Iran’s signals contradicted each other: Tehran offered through mediators to reopen Hormuz within seven days while the IRGC fired ballistic missiles at US warships and announced strikes on tankers. The argument here is that Iranian crisis decisions run through two channels, diplomatic and coercive, and that the only office able to bind them, the Supreme Leader, does not appear in the observable decision record. This structure lowers the credibility of Iranian commitments and helps explain the failure of the Islamabad Memorandum and the rejection of the seven-day plan. The period covered is June–September 2026, with emphasis on September.
2. Actors, interests and the credibility problem
Commitment credibility is defined here as the degree to which a counterpart perceives a state’s promise as enforceable and binding. It is distinct from intention: a government seeking a deal in good faith still offers a weak promise if it cannot control the implementing institutions. Jervis (1978) showed that cooperation under the security dilemma depends on each side reading the other’s intentions and moves correctly, and that ambiguous signals make even defensive steps look threatening. Beardsley (2008) argued that mediated agreements become vulnerable to reneging once the mediator’s inducements fade, a time-inconsistency problem. Together they predict that when a party’s internal decision structure cannot be read from outside, its signals become ambiguous and the cost of defecting falls.
The actors divide by channel. The diplomatic channel comprises the Foreign Ministry and the presidency, which handle mediators and proposals. The coercive channel comprises IRGC operations and the Majlis, whose security commission legislates on transit through the strait. Their stakes differ: the diplomatic channel gains from sanctions relief and frozen assets, while the coercive channel’s leverage rests on control of the strait. Open-source data on Iranian domestic politics for August–September are thin and coordination between the channels cannot be observed directly, so the inferences rest on observable outputs of the decision process.
3. The coercive channel in September
After the United States struck two Iranian state tankers for the first time on 1 September, Iran, according to Axios, fired about 25 ballistic missiles and sent roughly two dozen drones towards US bases in Bahrain (Ravid, 2026). On 5 September the IRGC claimed to have hit three tankers using “an unauthorized route” and three US-linked vessels; the next day Mohammad Bagher Qalibaf, Iran’s chief negotiator, announced that “the era of ‘proportionate responses’ is over” and that responses would be “faster, heavier, and more painful” (Brennan et al., 2026). In September the Majlis security commission approved bill provisions allowing the seizure of 20% of a violating ship’s cargo and the detention of the vessel until a penalty is paid (Brussels Signal, 2026). This step extends the coercive channel from military action into legislation: transit conditions in the strait become a matter of domestic law.
4. The diplomatic channel in September
Reuters reported that on 22 September, on the margins of the UN General Assembly, mediators shuttled between the two sides all day, and a senior Iranian official said Tehran could open Hormuz within seven days if Washington eased military pressure and lifted the blockade of Iranian ports (Slattery et al., 2026). The seven-day plan that became public on 24–26 September provided for a halt to regional fighting including Lebanon and Yemen, the release of frozen assets estimated at a minimum of $12 billion, the lifting of oil sanctions and the end of the US blockade, and left the opening of Hormuz to the seventh day (AFP, 2026; Hürriyet Daily News, 2026). Reuters, relaying a Wall Street Journal report based on US officials, said Trump had rejected the proposal (Holland & Hafezi, 2026). On 25 September Pezeshkian stated that Mojtaba Khamenei was in “quite good health” (Hürriyet Daily News, 2026). The statement cannot be independently verified; the need to make it indicates that questions about the leader’s condition persisted.
5. Where the credibility gap appears
Herald Business reported that the IRGC consolidated control over internal decision-making during the war (Do, 2026). The sources reviewed contain no crisis decision for August–September 2026 attributed directly to the Supreme Leader. From outside it cannot be read which centre has the final word: the Foreign Ministry that tabled the offer or the IRGC that determines behaviour in the strait. Cohesion means elites do not split openly, and no visible split suggests the Janes (2026) forecast has held. Credibility means the counterpart knows which institution will implement a promise and with what enforcement power. Iran in September displayed cohesion without credibility.
The Qalibaf statement deepens the ambiguity. Escalatory language came from the chief negotiator, the figure expected to belong to the diplomatic channel. The counterpart cannot tell whether a threat from the negotiating table is a bargaining tactic or a sign that battlefield decisions are taken independently of the talks; the signal ambiguity Jervis (1978) described here has an institutional source.
The sequencing of the seven-day plan can be read as a response to that ambiguity. It defers Iran’s main concession, the reopening of Hormuz, until after every US and regional step. When a party whose commitment cannot be verified asks for concessions first, the other side demands the same on the same grounds; the rejection follows from this mutual distrust.
6. The Islamabad Memorandum as the first test
The June–August sequence shows the same mechanism. The memorandum, signed under Pakistani mediation on 17 June (some sources give 18 June), set a 60-day window for a broader peace agreement, the lifting of the naval blockade within 30 days and an Iranian commitment to clear mines in Hormuz (Shamim, 2026). The Ever Lovely was struck on 25 June, the United States hit Iranian coastal facilities on 27 June, and Trump declared the deal over on 7 July (Shamim, 2026). Deputy Foreign Minister Gharibabadi announced on 18 July that all commitments under the memorandum were suspended (ProPakistani, 2026), and the 60-day window expired on 17 August. The collapse date is therefore disputed: political collapse on 7 July, formal Iranian suspension on 18 July, expiry on 17 August.
Beardsley’s (2008) time-inconsistency argument fits this path: the mediator’s momentum ran out within weeks because it did not change the incentives of the institutions charged with implementation. The diplomatic channel signed the mine-clearance commitment; its execution depended on military units in the strait. That distance between the signing channel and the implementing channel was the agreement’s weakest link. This is an inference, not a statement in the sources.
7. Alternative readings
The first alternative reading treats the two channels as one strategy in which the centre pairs coercion with offers to raise its bargaining position. The sources cannot exclude this. Even if it is correct, the credibility cost remains, because a counterpart that cannot distinguish a coordinated strategy from two uncoordinated centres discounts the promise in both cases. The second reading attributes the failures to US choices: Trump declared the memorandum over on 7 July, the September salvoes followed the US tanker strikes of 1 September, and Trump rejected the plan. This explains the timing of breakdowns; the Iranian record still shows no authority that could have guaranteed implementation had Washington accepted.
8. Outlook: Türkiye, Saudi Arabia and the World
Between October 2026 and 2027 the credibility gap depends on three conditions. The first is the US calendar: on 22 September Trump said he expected a deal “right after the election” (Schuler, 2026). If a post-November round opens, reciprocal step-by-step concessions with third-party verification could replace the unilateral deferral built into the seven-day plan. The second is Iran’s internal structure: public ownership of a deal by the Supreme Leader, or an arrangement placing implementation on the IRGC, would bind both channels; without it, a signed text risks the fate of the Islamabad Memorandum. The third is whether the cargo-seizure provisions become law, which would institutionalise the coercive channel.
For Türkiye, mediation is limited by the interlocutor problem: Ankara assisted in mediating the Hormuz talks in August, when Iran said it was close to agreement with Oman (NPR, 2026), but the sources do not confirm the route was used, and any technical arrangement depends on IRGC compliance. For Saudi Arabia, the problem lies in attribution: Riyadh must weigh Iranian statements without knowing whether the issuing channel controls forces in the field. Globally, the market effect of Iranian offers will stay limited until IRGC behaviour in the strait confirms them.
9. Conclusion
From June to September 2026, Iranian crisis decisions ran through two channels: negotiating language from the Foreign Ministry and the presidency, missile and tanker attacks from the IRGC, cargo-seizure provisions from a Majlis commission and escalatory language from the chief negotiator. No crisis decision in the reviewed sources is attributed to the Supreme Leader. Whether the channels form a coordinated strategy or independent centres cannot be determined from outside, and that indeterminacy is what generates the credibility cost. The unravelling of the Islamabad Memorandum and a plan that left Hormuz to the last day express the same problem. Until the distance between the channel that signs and the channel that implements closes, counterparts will read Iranian promises as bargaining positions.
SOURCES
AFP. (2026, 26 September). Iran offers seven-day plan to reopen Strait of Hormuz. The Vibes. https://www.thevibes.com/articles/world/127695/iran-offers-seven-day-plan-to-reopen-strait-of-hormuz
Beardsley, K. (2008). Agreement without peace? International mediation and time inconsistency problems. American Journal of Political Science, 52(4), 723–740. https://doi.org/10.1111/j.1540-5907.2008.00339.x
Brennan, D., El-Bawab, N., & Pereira, I. (2026, 6 September). US strikes oil tankers, Tehran claims attacks on US-linked vessels. ABC News. https://abcnews.com/International/live-updates/iran-live-updates-centcom-targeted-iranian-forces-posed/?id=136080582
Brussels Signal. (2026, 23 September). Kallas presses Tehran for toll-free passage through Hormuz. https://brusselssignal.eu/2026/09/kallas-presses-tehran-for-toll-free-passage-through-hormuz/
Do, H. (2026, 1 June). Iran’s president slams minority rule as resignation rumors swirl. The Herald Business. https://biz.heraldcorp.com/article/10774043
Holland, S., & Hafezi, P. (2026, 25 September). Trump rejects Iranian peace proposal, WSJ reports. Al-Monitor. https://www.al-monitor.com/originals/2026/09/allies-unite-behind-saudi-arabia-houthis-step-attacks
Hürriyet Daily News. (2026, 25 September). Iran proposes reopening Hormuz within seven days. https://www.hurriyetdailynews.com/iran-proposes-reopening-hormuz-within-seven-days-227341
Janes. (2026, 9 March). Appointment of Mojtaba Khamenei as Supreme Leader of Iran very likely indicates that elite cohesion will remain strong in the immediate term. https://www.janes.com/osint-insights/defence-and-national-security-analysis/appointment-of-mojtaba-khamenei-as-supreme-leader-of-iran-very-likely-indicates-that-elite-cohesion-will-remain-strong-in-the-immediate-term
Jervis, R. (1978). Cooperation under the security dilemma. World Politics, 30(2), 167–214. https://doi.org/10.2307/2009958
NPR. (2026, 6 August). Iran says it is close to reaching agreement with Oman to reopen Strait of Hormuz. VPM. https://www.vpm.org/npr-news/npr-news/2026-08-06/iran-says-it-is-close-to-reaching-agreement-with-oman-to-reopen-strait-of-hormuz
ProPakistani. (2026, 18 July). Iran suspends Islamabad MoU. https://propakistani.pk/2026/07/18/iran-suspends-islamabad-mou/
Ravid, B. (2026, 1 September). U.S. strikes Iran tankers under new “tanker for tanker” policy. Axios. https://www.axios.com/2026/09/02/iran-tankers-hormuz-attacks-oil
Schuler, M. (2026, 22 September). Trump calls for Iran’s economic isolation at UN as Tehran offers Hormuz reopening. gCaptain. https://gcaptain.com/trump-calls-for-irans-economic-isolation-at-un-as-tehran-offers-hormuz-reopening/
Shamim, S. (2026, 17 August). US-Iran Memorandum of Understanding expires: How and why it fell apart. Al Jazeera. https://www.aljazeera.com/amp/news/2026/8/17/us-iran-memorandum-of-understanding-expires-how-and-why-it-fell-apart
Slattery, G., Hafezi, P., & Slodkowski, A. (2026, 23 September). Trump threatens to annihilate Iran as diplomats push for deal at UN. Al-Monitor. https://www.al-monitor.com/originals/2026/09/tehran-hints-hormuz-talks-us-leaders-gather-un
Furkan Mahmut Tameroglu