Iran Update Evening Special Report: May 28, 2026

Data Cutoff: 2:00 PM ET

The Institute for the Study of War (ISW) and The Critical Threats Project (CTP) at the American Enterprise Institute are publishing daily updates to provide analysis on the war with Iran. The updates focus on US and Israeli strikes on Iran and Iran and the Axis of Resistance’s response to the strikes. The updates cover events from the past 24-hour period. 

NOTE: CTP-ISW will post morning social media threads on an as-needed basis starting on April 28, 2026, for the duration of the ceasefire. We will continue providing long-form analysis on the state of the Iran War in our daily Iran Update Special Reports. 

Key Takeaways:

• Western media reported on May 28 that US and Iranian negotiators have reached a 60-day memorandum of understanding (MoU), but the US and Iranian leaders who must approve the agreement—US President Donald Trump and Iranian Supreme Leader Mojtaba Khamenei, respectively—have not approved the “agreement” at this time. The details of the reported “agreement” are also unclear based on the wording and sourcing of the leaks of the agreement.
• Even if Iranian negotiators did offer some concessions, it is far from clear that senior decision-makers in Tehran, including Mojtaba and IRGC Commander Major General Ahmad Vahidi, are willing to make such concessions. Mojtaba’s recent public statements indicate that he is not willing to give up Iranian control over the Strait of Hormuz.
• The IRGC is using force to try to create the reality that Iran controls the Strait of Hormuz. US Central Command’s (CENTCOM) recent military strikes against Iran are part of an effort to deny Iran the ability to create that reality.
• The United States is taking steps to prevent Iranian efforts to establish a protection racket in the Strait of Hormuz. The US Treasury Department sanctioned the Persian Gulf Strait Authority (PGSA) on May 27 and warned that any actor that cooperates with the PGSA could face sanctions.

Toplines

Western media reported on May 28 that US and Iranian negotiators have reached a 60-day memorandum of understanding (MoU), but the US and Iranian leaders who must approve the agreement—US President Donald Trump and Iranian Supreme Leader Mojtaba Khamenei, respectively—have not approved the “agreement” at this time. The details of the reported “agreement” are also unclear based on the wording and sourcing of the leaks of the agreement.[i] Two unspecified US officials told Axios on May 28 that US and Iranian negotiators have reached a 60-day MoU to extend the ceasefire and launch negotiations on Iran’s nuclear program.[ii] The officials claimed that Iranian negotiators received the “necessary approvals” from “senior leadership” to sign the deal. Islamic Revolutionary Guards Corps (IRGC)-affiliated Tasnim News Agency, citing a source close to the negotiating team, denied that an MoU has been “finalized,” however.[iii] An unspecified source also told Israeli media that Mojtaba has not yet approved the “agreement.”[iv]  

The US officials told Axios that Iran would allow “unrestricted” shipping through the Strait of Hormuz, stop imposing tolls and harassing vessels in the strait, and remove naval mines within 30 days, while the United States would lift its naval blockade on Iranian ports.[v] The officials did not specify how the MoU defines “unrestricted” shipping. Iranian officials have repeatedly described the strait as “open” to shipping while forcing vessels to receive Iranian permission to pass through the strait and to use Iran’s illegal traffic separation scheme.[vi] Iranian officials have also claimed that Iran is charging vessels “protection fees” and “environmental fees” instead of “tolls.”[vii] The ambiguity around these terms makes it unclear whether Iranian negotiators have actually committed to any concessions in the reported MoU.  

Even if Iranian negotiators did offer some concessions, it is far from clear that senior decision-makers in Tehran, including Mojtaba and IRGC Commander Major General Ahmad Vahidi, are willing to make such concessions. Mojtaba’s recent public statements indicate that he is not willing to give up Iranian control over the Strait of Hormuz.[viii] IRGC-affiliated media has also insisted that Iran must receive economic relief—including the release of some of Iran’s frozen assets—before Iran will discuss its nuclear program.[ix] CTP-ISW continues to assess that Vahidi and his inner circle are currently dominating Iranian decision-making. The US officials told Axios that the United States would discuss sanctions relief and the release of Iran’s frozen assets during the 60-day negotiations period, in contrast to the Iranian regime’s demand for immediate economic relief upon the signing of an agreement. If Iranian negotiators did agree to postpone the discussion of economic relief to the 60-day negotiations period, this would indicate that Iranian negotiators may not be aligned with Mojtaba and Vahidi. Anti-regime media, citing a source close to the negotiations, reported on May 28 that there are doubts among unspecified individuals about Iranian Parliament Speaker Mohammad Bagher Ghalibaf and the negotiating team’s coordination with Mojtaba, which further suggests that the terms in the reported US-Iran MoU may not reflect the positions of key Iranian leaders in Tehran.[x]

The IRGC is using force to try to create the reality that Iran controls the Strait of Hormuz. US Central Command’s (CENTCOM) recent military strikes against Iran are part of an effort to deny Iran the ability to create such a reality. Iranian state media claimed on May 28 that the IRGC Navy issued a “stern warning” to four vessels that attempted to pass through the Strait of Hormuz without Iranian permission.[xi] The report claimed that the IRGC Navy seized two of the vessels and forced the other two vessels to turn around.[xii] US CENTCOM reported on May 28 that US forces intercepted five Iranian one-way attack drones that threatened US forces and commercial shipping in the strait.[xiii] CENTCOM added that US forces struck an Iranian drone launch site in Bandar Abbas, Hormozgan Province, that was preparing to launch a sixth drone.[xiv] It is possible that the Iranian drones were targeting the vessels that Iranian media claimed attempted to transit through the strait without coordinating with Iran. Iran has repeatedly used force, including attacks on commercial vessels and naval mines, to force vessels to transit through its illegal traffic separation scheme and comply with Iranian transit regulations. US forces recently struck two IRGC Navy mine-laying vessels on May 25. Iran responded to the US strikes by launching a ballistic missile at an unspecified US airbase in Kuwait, but Kuwaiti air defenses intercepted the missile.

CTP-ISW is tracking initial IRGC-affiliated media reporting of Iranian missile attacks launched from southern Iran targeting US naval vessels in an unspecified location in the Persian Gulf as of 3:58 PM ET on May 28.[xv] CTP-ISW will provide further analysis about these reports on May 29.

The United States is taking steps to prevent Iranian efforts to establish a protection racket in the Strait of Hormuz. The US Treasury Department sanctioned the Persian Gulf Strait Authority (PGSA) on May 27 and warned that any actor that cooperates with the PGSA could face sanctions.[xvi] The PGSA is an organization that Iran established to formalize its control over the strait and force commercial vessels to pay tolls and coordinate their movements with Iran.[xvii] US Treasury Secretary Scott Bessent also threatened to economically target any actors, including Oman, that directly or indirectly facilitate tolls in the strait.[xviii] Bessent’s comments follow multiple reports that Iran has discussed establishing a system with Oman to jointly collect tolls from vessels that transit through the strait .[xix]

US-Iran Negotiations

See topline section.

Maritime Activity in the Strait of Hormuz and Persian Gulf

See topline section.

US-Israeli Air Campaign

See topline section.

Regime Dynamics in Iran

The Iranian Parliament re-elected Mohammad Bagher Ghalibaf as parliament speaker for his seventh consecutive term in the Iranian Parliament's annual presidium election on May 25.[xx] It is very rare, if not unprecedented, for parliamentarians to oust the incumbent parliament speaker during the annual presidium election, and it would have therefore been noteworthy if parliamentarians had voted to remove Ghalibaf. Ghalibaf’s removal would have been particularly notable given the role he has played in leading Iran’s negotiating delegation in recent months. Ghalibaf won 235 votes from the 285 parliamentarians who voted. The other two candidates for parliament speaker were ultraconservative Paydari (Stability) Front candidate Mohammad Taghi Naghdali and Sunni candidate Osman Salari, who received 29 and seven votes, respectively.[xxi] Parliament also re-elected Ali Nikzad and Hamid Reza Haji Babaei as deputy parliament speakers.[xxii] Ghalibaf has served as parliament speaker since 2020, before which Ali Larijani held the position for 12 years.[xxiii]

Iran’s Axis of Resistance

Lebanese Hezbollah and the Israeli Campaign in Lebanon

The Israel Defense Forces (IDF) conducted a strike in Beirut’s vicinity for the first time since May 6, after the IDF reportedly received US approval to target Hezbollah-affiliated commanders in the area.[xxiv] The IDF announced that it conducted a strike in Beirut on May 28.[xxv] Israeli media and open-source intelligence (OSINT) accounts reported that the strike targeted Imam Hussein Division Missile Force Commander Ali al Husseini in Chouaifet, Aley District, which is located in Beirut’s metropolitan area.[xxvi] The IDF has not confirmed that its strike targeted Husseini at the time of this writing, however. The IRGC Quds Force uses the Imam Hussein Division to conduct attacks against the IDF and Israel.[xxvii] The IDF struck and killed former Imam Hussein Division Commander Hassan Ali Marwan in Beirut on March 17.[xxviii] The IDF strike in Chouaifet marks the first IDF strike in Beirut’s vicinity since the IDF killed Hezbollah Radwan Force Commander Ahmad Ghaleb “Malik” Balout in Beirut’s southern suburbs on May 6.[xxix] The IDF’s strike follows recent reports that US officials support allowing the IDF to target Hezbollah commanders in Beirut.[xxx] A senior Israeli official told Israeli media on May 26 that the United States told Israel not to conduct large attacks in Beirut but authorized Israel to conduct targeted strikes against Hezbollah commanders.[xxxi]

The IDF has expanded its ground and air campaigns in Lebanon in recent days and has made limited advances beyond the “Yellow Line.”[xxxii] The IDF confirmed on May 28 that it has conducted “raids” beyond the “Yellow Line” to push Hezbollah fighters deeper into Lebanon and protect Israeli forces in southern Lebanon and northern Israel from Hezbollah first-person view (FPV) drone attacks.[xxxiii]  Israeli Prime Minister Benjamin Netanyahu said on May 26 that the IDF will seize “strategic positions” during expanded ground operations and confirmed on May 28 that Israeli forces have advanced north of the Litani River.[xxxiv] An OSINT analyst posted satellite imagery on May 28 showing several IDF tanks positioned north of the Litani River in Yohmor, Nabatieh District.[xxxv] The analyst previously posted imagery on May 26 showing IDF tanks in nearby Zawtar al Charqiyeh, Nabatieh District, which was the IDF’s bridgehead for ground operations north of the Litani.[xxxvi] Hezbollah claimed on May 27 that it used direct fire on Israeli forces in Zawtar al Charqiyeh, which Hezbollah has typically avoided except for the group’s recent attempts to defend against Israeli ground advances.[xxxvii] The IDF has also expanded its air campaign in Lebanon and claimed that it has struck nearly 700 Hezbollah targets since May 24.[xxxviii] The IDF struck at least six Hezbollah sites in the northern Beqaa Valley, in addition to striking around 15 targets in the vicinity of Tyre on May 27 and 28.[xxxix] The IDF also issued an order on May 27 for civilians to evacuate all Lebanese territory south of the Zahrani River for the first time and declared all territory south of the river a ”combat zone.”[xl]

Other Axis of Resistance Activity

Nothing significant to report.