The Italian Institute for International Political Studies (ISPI) reported on December 24 that unspecified sources in Tehran told ISPI that Iranian Supreme Leader Ali Khamenei authorized the initial development of miniaturized nuclear warheads for ballistic missiles in October 2025.[1] ISPI is the only source that has reported information about the supreme leader authorizing the development of miniaturized nuclear warheads.[2] This source has not previously offered in-depth analysis of or verifiable information about the Iranian nuclear program. ISPI reported that Khamenei did not authorize uranium enrichment beyond 60 percent, however.[3] ISPI noted that producing deliverable, miniaturized nuclear warheads poses significant technical challenges and requires weapons-grade uranium enriched to 90 percent, which Iran does not currently possess.[4]
Iran has previously explored alternative nuclear weapon paths that do not require warhead miniaturization. The New York Times reported in February 2025 that a “secret team” of Iranian weapons engineers and scientists is “exploring” a faster approach to building a nuclear weapon in a “matter of months.”[5] Unspecified US officials told the New York Times that Iran could build an “older-style nuclear weapon” using the new approach, but noted that such a weapon would not fit on a ballistic missile and would likely be less reliable than a modern weapon.[6]
https://understandingwar.org/research/middle-east/iran-update-december-24-2025/
Iran Update, December 26, 2025
The Islamic Revolutionary Guards Corps (IRGC) seized a “foreign” tanker near Gheshm Island in the Strait of Hormuz on December 24. The IRGC claimed the tanker was smuggling four million liters of oil.[1] The IRGC Navy also detained 16 non-Iranian crew members, according to local judicial authorities in Hormozgan Province on December 26.[2] Neither the IRGC nor Iranian media has disclosed the name of the tanker or the nationality of its crew members. CTP-ISW is unable to confirm the incident or verify the name of the tanker using commercially available maritime tracking data at this time.
It is possible that Iran seized the tanker in response to recent US seizures of tankers in the Caribbean Sea. The US Coast Guard seized a reported ghost fleet tanker, the Bella 1, in an unspecified location in the Atlantic Ocean on December 25 after a five-day pursuit through the Caribbean.[3] An attributed IRGC X account posted the following Islamic verse: ”throw the enemy’s stone back in the same direction it was thrown from, because evil is repelled only by evil” on December 24, around the same time as the IRGC Navy’s seizure of the tanker near Gheshm Island.[4] The same account quoted the following Quranic verse at the same time of the seizure of the oil tanker Talara on November 14: “So whoever has assaulted you, then assault him in the same way that he has assaulted you.[5] US special operations forces intercepted a shipment of military-related equipment from China to Iran in the Indian Ocean at some point in November 2025.[6] It is unclear if the IRGC statement or the Talara seizure on November 14 was in response to this seizure. The seizure of the Talara also followed an unspecified explosion on the M/V Falcon in the Red Sea in October.[7] The non-profit United Against Nuclear Iran reported that the Falcon was an Iranian shadow fleet vessel that transports illicit Iranian oil.[8] The United States has also seized three oil tankers near Venezuela in December 2025.[9]
Iran announced on December 21 the deployment of Artesh Naval flotillas to escort commercial vessels, amid Iranian concern over US tanker seizures. Iranian Foreign Affairs Ministry spokesperson Esmail Baghaei and the Embassy in Caracas called the US seizure of oil tanker Skipper off the coast of Venezuela on December 10 an act of “piracy.”[10] The Skipper has historically transported illicit Iranian oil.[11] Artesh Navy Commander Admiral Shahram Irani announced on December 21 that the Artesh Navy deployed the 103rd and 104th flotillas on overseas missions and added that one of the fleets will be “tasked with escorting commercial ships.”[12] CTP-ISW cannot determine the composition of the Artesh 103rd and 104th flotillas as of the time of writing.
https://understandingwar.org/research/middle-east/iran-update-december-26-2025/