Ria Reddy, Katherine Wells, Kelly Campa, Avery Borens, Ben Schmida, Alexandra Braverman, Andie Parry, and Annika Ganzeveld

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Iran may have jammed vessel navigation systems in the Strait of Hormuz in order to set conditions to seize vessels that inadvertently enter Iranian territorial waters as a result of navigation issues. The United Kingdom Maritime Trade Operations (UKMTO) reported that several vessels experienced Global Positioning System (GPS) interference in the Strait of Hormuz for several hours on May 18. GPS interference disrupts ships’ ability to navigate, and they may veer off course as a result. GPS interference around the Strait of Hormuz can cause vessels to inadvertently enter Iranian territorial waters, which Iran can then use to justify seizing vessels . Iran previously conducted GPS jamming in 2019 to try to lure vessels into Iranian waters. The GPS jamming in 2019 was part of a broader Iranian response to the US "maximum pressure” campaign that also included seizing and attacking vessels. The recent GPS interference incidents come after Iranian Armed Forces General Staff Chief Major General Mohammad Bagheri threatened on May 12 that Iran would retaliate by disrupting international commercial shipping, among other things, "if the US military makes a mistake.” Bagheri was likely referring to a potential US strike on Iranian nuclear or energy facilities. Iran also deployed missile-capable fast attack craft (FAC) as well as geospatial intelligence and surveillance technology to Iranian islands in the Persian Gulf on May 12. Iran can use FAC to attack and harass ships.

This recent series of events suggests that Iran may be in the very early stages of an escalation campaign against international shipping around the Strait of Hormuz. Iran previously threatened international shipping through this important waterway in 2019 in response to US President Donald Trump’s “maximum pressure” strategy. Iran’s preparations for its campaign in 2019 mirror actions that Iran is taking today. Iranian officials inspected Iranian military sites near the Persian Gulf in 2019 before Iran conducted attacks on vessels. Senior Iranian military commanders, including Bagheri and Artesh Navy Commander Rear Admiral Shahram Irani, have recently visited Islamic Revolutionary Guards Corps (IRGC) and Artesh Navy sites along the Persian Gulf coast. Iran later used drones to harass vessels passing through the Strait of Hormuz and used GPS jamming to coax vessels into Iranian territorial waters. IRGC-affiliated media recently published videos of Iranian drones following US naval vessels in the Persian Gulf. It is unclear whether Iran is preparing for a campaign targeting international shipping in the Strait of Hormuz or trying to signal to the United States that it can threaten freedom of navigation through the Persian Gulf to try to deter a potential US strike on Iran.

Key Takeaways:

• Iran may be in the very early stages of an escalation campaign against international shipping around the Strait of Hormuz. Iran may have jammed vessel navigation systems in the Strait of Hormuz in order to set conditions to seize vessels that inadvertently enter Iranian territorial waters as a result of navigation issues. The United Kingdom Maritime Trade Operations reported that several vessels experienced GPS interference in the Strait of Hormuz for several hours on May 18. GPS interference around the Strait of Hormuz can cause vessels to inadvertently enter Iranian territorial waters, which Iran can then use to justify seizing vessels. Iran previously conducted GPS jamming in 2019 to try to lure vessels into Iranian waters. The GPS disruptions on May 18 come after a possible Iranian vessel recently harassed a commercial vessel in the Persian Gulf on May 10.

• The United States appears to have adopted a more cohesive position on Iran's uranium enrichment as zero uranium enrichment continues to be the main sticking point in the US-Iran nuclear negotiations. US Special Envoy to the Middle East and lead US negotiator Steve Witkoff stated on May 18 that enrichment is the Trump administration's "one very, very clear redline." Iranian Foreign Affairs Minister Abbas Araghchi called Witkoff's remarks "far from reality" and emphasized that Iran will continue to enrich uranium. The Guardian separately reported on May 15 that mediators urged Iran to accept a deal in which Iran would suspend uranium enrichment for three years to "build trust" with the United States. The proposal reportedly stipulates that Iran would be allowed to resume uranium enrichment at 3.75 percent, similar to the Joint Comprehensive Plan of Action (JCPOA) limit, after three years. It is unclear if Iran would accept a temporary suspension of its uranium enrichment.

• The Islamic State of Iraq and Syria (ISIS) has developed the ability to conduct attacks in the Middle Euphrates River Valley with logistically advanced vehicle-borne improvised explosive devices (VBIED). ISIS attacked a General Security Service (GSS) police station with a VBIED in al Mayadin, Deir ez Zor Province, on May 18. The attack severely damaged the police station. The production of a VBIED powerful enough to crater concrete and damage nearby cement buildings requires significant logistical capabilities, including the ability to procure and modify vehicles, manufacture explosives, and develop a detonation system that is either remote or vehicle-operated. This attack indicates that ISIS has established a relatively sophisticated logistics network near al Mayadin to produce VBIEDs and is emblematic of ISIS’s continued presence in eastern Syria.

• Syrian security forces raided ISIS cells in Aleppo City on May 17. The GSS killed two ISIS members and arrested four others during raids in al Jazmati and al Haydariyah, Aleppo City. A separate ISIS member detonated a suicide vest during one of the raids. ISIS fighters killed two GSS members in small arms clashes during the raids.

• The Syrian transitional government's nominal integration of some armed groups into the Ministry of Defense (MoD) in order to rapidly assert state control over Syrian factions risks diminishing the government’s command and control over these groups. Syrian Defense Minister Marhaf Abu Qasra announced on May 17 that armed groups that have not yet integrated into state security services must do so within 10 days or face unspecified penalties. The Syrian MoD has effectively re-flagged several factions as divisions or brigades within the new army without requiring commanders to reform or restructure their forces. Syrian media reported on May 18 that the Syrian government re-flagged the Turkistan Islamic Party (TIP) as the new 84th Division in the Syrian army.

• Re-flagged Syrian National Army (SNA) factions are far less likely to adhere to the formal chain of command than groups that have subordinated themselves to HTS. These less responsive groups risk alienating minority groups, such as the Kurds, by conducting unsanctioned operations or attacks against these groups. Both anti-Syrian Democratic Forces (SDF) and pro-Kurdish media reported that the SDF and SNA factions advanced toward each other west of Tishreen Dam in the Manbij countryside on May 18 and briefly exchanged fire in the area on May 19. It is unclear if Damascus sanctioned the SNA’s recent activity near Tishreen Dam. The existence of SNA-dominated army units that do not answer to Damascus risks discouraging Kurdish militants from integrating into the state due to the SNA’s historic abuses against the Kurdish population.

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