Iran Update, October 21, 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 updates Monday through Friday to provide analysis on the war with Iran and the broader Middle East. Weekday updates cover events from the past 24-hour period, whereas weekend updates are abbreviated and cover the Houthi-Saudi conflict and major breaking developments related to the war with Iran. 

Key Takeaways:

• Iran may have used more accurate systems to attack commercial shipping in the Strait of Hormuz over the past two weeks, which is consistent with CTP-ISW's October 5 assessment that Iran is likely improving its ability to target maritime traffic in the waterway after it faced targeting constraints in August and early September 2026.
• Iran may be using drones or cruise missiles equipped with infrared terminal guidance systems to target some of these vessels. Repeated successful strikes on engine rooms require weapon systems with a sufficient degree of precision, which suggests that Iran is likely firing anti-ship cruise missiles (ASCM) or IR-equipped drones.
• The Washington Post, citing oil price-tracking firm Kpler, reported that the number of barrels of oil exported per day is approaching prewar daily averages after increasing from mid-August to late September. Iran likely launched its recent waves of attacks on civilian ships in an attempt to change these conditions in Iran’s favor.

Toplines

Iran may have used more accurate systems to attack commercial shipping in the Strait of Hormuz over the past two weeks, which is consistent with CTP-ISW's October 5 assessment that Iran is likely improving its ability to target maritime traffic in the waterway after it faced targeting constraints in August and early September 2026.[i] Several shipping and maritime security officials told Bloomberg on October 20 that at least five of the 23 recorded attacks on vessels in or near the Strait of Hormuz in the first two weeks of October struck commercial vessels’ engine rooms.[ii] Bloomberg added that no reported incidents in the strait in September involved engine-room strikes.[iii]

Iran may be using drones or cruise missiles equipped with infrared terminal guidance systems to target some of these vessels. Repeatedly striking engine rooms requires weapon systems that can distinguish between an engine room and other possible targets on a vessel. These weapons would need to make their terminal approach without human guidance, because human guidance would require connectivity (likely via radio frequency) that would be challenging due to distance and jamming in the Strait of Hormuz. This would likely require a terminal guidance system equipped with a sensor that could distinguish the engine room from the rest of the vessel.[iv] An infrared seeker is the most likely tool for such a task, therefore, given the limitations inherent in the employment of electro-optical seekers. An electro-optical seeker would need contrast between the target and the background, which would be sufficient to target a cargo vessel but not the engine room on that vessel. Iran has anti-ship cruise missiles equipped with IR seekers, and Russia has previously modified the Shahed-136 to carry an IR seeker.[v] It is not clear if Iran has made similar modifications.[vi]

It is unlikely that Iran is continuing to use drones that rely on radio frequencies for guidance, given the jamming prevalent in the strait. Drones that require an uninterrupted radio frequency (RF) data link are vulnerable to jamming, interception, or line-of-sight signal loss. RF jamming has been frequently observed in the strait, which would theoretically complicate the accuracy and precision of Iranian strikes.[vii] This suggests that Iran is more likely to be relying on an IR homing-equipped weapons system that does not require human terminal guidance, given that these characteristics would ensure that the system is unaffected by jamming or spoofing.

Repeated successful strikes on engine rooms also require weapon systems with a sufficient degree of precision, which suggests that Iran is likely firing anti-ship cruise missiles (ASCM) or IR-equipped drones. Attacks on ships’ engine rooms almost certainly require a projectile that can impact a ship from a horizontal flight path with a high degree of accuracy. Ballistic missiles descend on near-vertical trajectories with massive warhead yields.[viii] A ballistic missile could not hit the engine room without attacking it from above, risking destruction of the vessel’s bridge—a fact that would surely be reported.  Low-altitude, sea-skimming ASCMs equipped with IR seekers hit vessels from the side, which allows them to hit engine rooms directly without destroying the whole ship or causing mass casualties (see below).

Iran is almost certainly also using other anti-ship weapon systems—without human terminal guidance—to hit ships in the strait, in cases it is not intentionally targeting engine rooms. Eighteen out of Iran’s 23 recorded attacks in the first two weeks of October did not necessarily target the ship’s engine room, according to Bloomberg.[ix] Iran could be using drones or ASCMs equipped with standard inertial navigation systems and active radar homing to target commercial shipping in general. The combination of inertial navigation systems and active radar homing is highly resilient against jamming.[x] Active radar seekers lock onto a target vessel’s overall radar cross-section, automatically steering the missile into the center of mass of the ship’s hull rather than a specific heat-emitting compartment.[xi]

Naval mines may also present a serious threat to commercial shipping, but mines cannot selectively target a ship’s engine room and generally rely on hull contact, magnetic signatures, or acoustic pressure.[xii] Iran has repeatedly claimed in recent weeks that targeted vessels struck naval mines, likely in order to reinforce the perception that routes outside Iranian control remain unsafe.[xiii] US CENTCOM stated on October 8 that ”primary transit lanes“ through the Strait of Hormuz remain cleared of mines, however.[xiv] International Maritime Organization Secretary-General Arsenio Dominguez warned on October 20 that Iranian forces ”still have mines” and that it is difficult to verify the level of threat they pose.[xv]

The increase in Iranian attacks on vessels is part of the ongoing Iranian campaign to pressure the United States to meet Iranian demands, including control over the strait, by driving up global prices. The Washington Post, citing oil price-tracking firm Kpler, reported that the number of barrels of oil exported per day is approaching prewar daily averages after increasing from mid-August to late September.^[xvi] The report attributed the rise in oil exports to US efforts to restore freedom of navigation in the strait. Recent US successes in facilitating the flow of oil out of the strait undermine Iranian claims of control over the waterway and reduce the Iranian regime’s leverage to achieve Iranian war aims. Iran likely launched its recent waves of attacks on civilian ships in an attempt to change these conditions in Iran’s favor. Two Iranian officials told The Washington Post on October 19 that the regime is "focused on" driving up global oil prices in order to exert leverage over US President Donald Trump before the midterm elections on November 3.[xvii] 

US and Partner Military Operations

Nothing significant to report.

Iranian Strike Campaign

• Assessed Iranian War Aims:
  • Secure international recognition of Iranian control over the Strait of Hormuz
  • Degrade the US ability and willingness to continue the war
  • Restore deterrence vis-à -vis the United States and its regional partners
  • Divide the United States and Israel from the Arab states

See topline section.

US-Iran Negotiations

Nothing significant to report.

Iranian Domestic Affairs

Iranian media claimed that Parliament Speaker Mohammad Bagher Ghalibaf met with Supreme Leader Mojtaba Khamenei.^[xviii] IRGC-affiliated Tasnim News Agency reported on October 21 that Ghalibaf met with Mojtaba to discuss military, economic, and political developments.[xix] Mojtaba has not made any public appearances since he was selected as supreme leader. Several news organizations have reported that Mojtaba was seriously wounded or incapacitated in the strike that also killed former Supreme Leader Ali Khamenei.[xx]

Lebanon

Nothing significant to report.

Iraq

The Iraqi federal government likely closed al Sheeb border crossing between Iraq’s Maysan Province and Iran’s Khuzestan Province on October 21 in response to US pressure on the Iraqi government to restrict trade with Iran.[xxi] The Iranian Interior Ministry spokesperson confirmed the crossing’s closure on October 21 and added that Iraq did not give Iran advance notice.[xxii] An Iraqi border official told Western media on October 21 that Iraqi authorities closed al Sheeb crossing to ”review security.” Two unspecified political sources told Agence France Press on October 21 that the United States is ”pressuring” the Iraqi federal government to close the majority of its border crossings with Iran.[xxiii] Iraq’s closure of this border crossing comes after Pakistan closed two of its key border crossings with Iran on October 17, which will likely further disrupt Iran’s use of overland trade channels.[xxiv] The closure of these three border crossings will likely exacerbate the effects of the economic restrictions that Iran currently faces. Iran has increasingly relied on overland trade routes in recent months as the United States has constrained Iran’s ability to trade by sea and air.[xxv] 

The Iraqi federal government has taken some steps to limit the Houthis' presence in Iraq, likely in response to US and Saudi pressure on the Iraqi government to prevent Iranian-backed militia attacks on neighboring countries. Iraqi government sources told US-funded, regional media on October 21 that Iraqi Prime Minister Ali al Zaydi ordered the closure of unspecified Houthi-owned offices in Iraq and the expulsion of any Houthi members who are "active" with Iranian-backed Iraqi militias.[xxvi] The Houthis maintain an active presence in Iraq, including at a headquarters in Baghdad’s Jadriyah neighborhood, and have coordinated with Iraqi militias in recent months to conduct attacks on neighboring countries such as Saudi Arabia.[xxvii] Zaydi's order comes amid US and Saudi pressure on the Iraqi government to disarm Iranian-backed Iraqi militias and prevent militia attacks on neighboring countries.[xxviii]  The Iraqi government will likely face significant obstacles to identifying and expelling all the Houthi members who worked with Iraqi militias since the Houthis have historically taken steps to obfuscate their involvement in Iraqi militia attacks.[xxix]  

Arabian Peninsula

Yemeni government-aligned forces, supported by Saudi air power, are engaging Houthi fighters in contested territory south of Taiz City, likely in order to try to break the Houthis' encirclement of government-aligned forces in central Taiz Governorate. Geolocated footage showed Yemeni government-aligned forces operating in previously Houthi-occupied territory in Misrakh District south of Taiz City on October 21.[xxx] The presence of Yemeni government-aligned forces in these areas suggests that this area may now be contested, particularly alongside Yemeni government reports of Saudi airstrikes in al Misrakh District on October 21 that presumably targeted Houthi fighters, which suggests that there is still a Houthi presence in the area.[xxxi] Yemeni government-aligned forces have engaged Houthi fighters south of Taiz City in recent days in order to attempt to break the Houthis' encirclement of central Taiz Governorate.[xxxii] Yemeni government-aligned forces' operational environment in Taiz Governorate will not meaningfully improve until the Yemeni government-aligned forces recapture Houthi-held main ground lines of communication between Taiz and Aden Governorates, however.[xxxiii]

Yemeni government-aligned forces separately continued to engage Houthi fighters near the contested town of Murad, south of Dhubab Airport on the coastal plain on October 21.[xxxiv] Geolocated footage originally published on October 19 separately shows Yemeni government-aligned forces firing an anti-tank guided missile at Houthi positions in Murad.[xxxv] Yemeni government-aligned forces regained control of Dhubab Airport on the southern Red Sea coastal plain on October 15 but fighting south of the airport suggests that this area remains contested by Houthi fighters and Yemeni government-aligned forces.[xxxvi]

The Houthis have continued to target Yemeni government-controlled airports in likely effort to disrupt external supply routes and constrain the government's ability to receive military aid. The Houthis struck a Yemeni government military camp at Aden International Airport and al Rayyan International Airport in Mukalla, Hadramawt Governorate, with drones and ballistic missiles on October 21.[xxxvii] The Houthis claimed that the latter attack targeted Saudi weapons shipments to the Yemeni government at al Rayyan International Airport.[xxxviii] The Houthis have previously claimed to target Saudi weapons shipments to the Yemeni government at Aden International Airport in early October, shortly after Saudi Arabia and Pakistan delivered military equipment to Yemeni government-aligned forces in Aden in September.[xxxix] Houthi strikes on Yemeni government-controlled airports in Aden and Hadramawt could constrain Saudi coalition efforts to resupply Yemeni government-aligned forces across different fronts.

The Houthis have continued to attack targets across Saudi Arabia to impose economic and political costs on Saudi Arabia and compel Saudi Arabia to capitulate to Houthi demands. The Saudi Joint Forces Command reported on October 21 that Saudi air defenses intercepted at least seven drones near Medina City, Eastern Province, and in southern Saudi Arabia.[xl] The Houthis denied the October 21 attack on Medina or attacking any other parts of Saudi Arabia, however.[xli] The Houthis previously targeted a power station in Medina on September 29.[xlii]  The Houthis have repeatedly targeted Saudi oil facilities, airports, and other civilian infrastructure as part of their ongoing strike campaign.[xliii] The Houthis likely seek to pressure Saudi Arabia to halt military operations and accept Houthi demands, which include lifting Saudi controls on Houthi-controlled ports and airports and granting the Houthis control over Yemen’s oil and gas resources.[xliv]