PolicyWatch 3191 –  September 26, 2019

By working effectively with the UN, Washington and Riyadh can help foster global consensus on Iran’s culpability, creating a firm basis for multilateral censure that could induce caution in Tehran.

On September 23, Britain, France, and Germany issued a joint statement on the strike against Saudi oil facilities at Abqaiq and Khurais, noting, “It is clear to us that Iran bears responsibility for this attack. There is no other plausible explanation.” Tehran continues to deny its involvement, however, so the international community will need to see convincing evidence before taking concerted diplomatic action. A multilateral forensic investigation appears to be in the works, potentially involving the UN and a range of member states. To achieve broad-based consensus, this investigation must be viewed as professional and impartial, balancing the need for quick results against a comprehensive and clear statement of the facts by neutral parties.


Washington’s incorrect 2002 assessment regarding Iraqi weapons of mass destruction has cast a long shadow over subsequent U.S. efforts to present evidence to a skeptical international community, including the current situation. Many officials are also nervous about giving the Trump administration a de facto green light for punitive actions that could lead to a regional conflict or deepen the Iranian nuclear problem.

As they attempt to leap these hurdles, U.S. and allied officials will have to sort through three main theories about where the September 14 attack came from:

  • Yemen. On the day of the combined drone and cruise missile attack, the Iranian-linked Houthi rebels in Yemen claimed responsibility for it. Yet they did the same after Saudi Arabia was hit by drone strikes on May 14—an attack that was later definitively found to originate from Iraq. More to the point, the United States quickly ruled out Yemen as a possible source for the latest strike, and various observers have pointed out that the eighteen drones used in the attack could not have flown that far.
  • Iraq. Some have questioned whether Iranian proxy groups in Iraq may have launched the attack. On September 15, Iraqi prime minister Adil Abdulmahdi denied this claim, and the U.S. government echoed his assessment the next day.
  • Iran. After ruling out Yemen and Iraq, Washington concluded that the strike involved Iranian weapons launched from Iranian territory. The evidence supporting this stance has yet to be released, but social media videos suggest the incoming drones and missiles were spotted and heard entering Saudi Arabia near its border with Iraq and Kuwait, indicating they may have been fired from southern Iran and crossed southern Iraq.

Proving the third theory requires Saudi Arabia to meet the evidentiary gold standard: showing that the weapons were not only of Iranian origin, but also launched from Iran. Yet Tehran would still bear considerable responsibility if the weapons were of Iranian origin but launched from another country.


Previous efforts to identify Iranian weapons can be instructive for investigators as they attempt to determine the source of the drones and missiles used on September 14. In 2016, the inclusion of independent weapon technical intelligence specialists and a dedicated UN Panel of Experts (PoE) was essential in revealing the Iranian provenance of multiple weapon systems employed by Houthi forces—a task that the Saudi-led coalition had mishandled until that point. Among other findings, investigators proved that Iran had provided small arms and light weapons, improvised explosive devices (IEDs), drones, missiles, and the technology necessary to convert a Shark-33 boat into a guided water-borne IED (WBIED).

Such conclusions can be reached via careful examination of a weapon’s internal components, since the materiel that Iran uses or provides to others often contains similar commercial and bespoke parts. For example, weapons used for past attacks in Yemen, Israel, and Bahrain contained identical branded microcontrollers and heat-shrink wire covering, enabling authorities to conclusively trace them back to Iran. In another case, Qiam-1 missiles delivered to Yemen still bore stamps and quality assurance stickers from their Iranian manufacturers.

The Saudis have strengthened their engagement with the Yemen PoE since 2018 and should be applauded for immediately inviting UN investigators to help look into the latest attack. Yet the kingdom needs more help with how it handles evidence. Its September 18 presentation of drone and missile fragments did not “tell the story” in a manner that most observers would understand or find convincing. Riyadh also needs assistance in recording and documenting the recovery, transfer, and display of materiel to ensure chain of custody, and in keeping materiel from different attacks from being comingled or otherwise “contaminated” through storage in a single warehouse.

Although proactive and sustained engagement with the Yemen PoE can help ameliorate such problems, the UN is not infallible in evidentiary matters. This was demonstrated in a 2018 PoE report that claimed a servomotor from a Houthi drone came from an Iranian distributor—an impossible finding because there was no way to conclude that just from the type of model. The UN could only have drawn that conclusion if unique serial numbers on the servomotor were traceable to a specific vendor, but no serial numbers were known. Besides putting the integrity of UN reporting at risk, such mistakes highlight the under-resourced nature of the PoE system, where a single “arms expert” is expected to be master of all domains, from pistols to ballistic missiles and everything in between.

The Yemen PoE is also constrained by its own reporting schedule—its habit of delivering classified half-yearly reports and releasing an annual public report around January may not fit the present need for quick, impartial reporting. To facilitate more rapid analysis and release of information, the UN should contract experienced and reputable commercial weapons technical intelligence organizations.


U.S. officials probably have access to satellite/drone imagery, electronic intelligence, and/or intercepted communications that prove the attack was launched from inside Iran. Normally, they would hesitate to reveal such evidence for fear of compromising sources and methods, but this case should be an exception. At a critical moment for U.S. credibility at the UN, and following one of Iran’s gravest violations of global security, it may be worth going the extra mile to convince the international community. There is precedent for breaking this intelligence taboo—in 1983, the United States released intercepted radio communications to prove that the Soviets deliberately shot down Korean Air 007.

In the current case, authorities may be able to recover GPS waypoint and flight data from the guidance units of the weapons involved. If so, they must provide this data and access to the original hard drives to UN investigators, along with any chain of custody records. This will enable the UN to verify not only the trajectory of the weapons, but also whether they were actually recovered from the September 14 attack site.

The necessity of this step was underlined by the Shark-33 WBIED that the Saudi-led coalition captured in Yemen in early 2017. Riyadh never gave the UN access to data from the boat’s onboard computer system, which contained images from inside the Islamic Revolutionary Guard Corps facility where the computer was constructed and exact GPS coordinates from the Iranian factory. The UN was also denied information on where the boat was recovered. As a result, it was unable to conclude that Iran had helped convert the boat into a WBIED. When much of this information was later released to the public, it showed that the Saudis had wasted what should have been an intelligence slam dunk.


Because the U.S. and Saudi governments both suffer from trust deficits on matters like Iranian attacks, they should err on the side of greater transparency in this case and let the evidence speak for itself. This means letting the UN or other neutral actors present the case in public. As Britain, France, and Germany have already acknowledged, the existing evidence is compelling, so only clumsy handling, sharing restrictions, or poor presentation can make it less convincing. Washington should also nudge Riyadh to make use of independent weapon technical intelligence specialists in order to improve evidence handling. And in the longer term, it should support increased funding for the UN PoE system so that it can develop and retain the expertise needed to deliver unimpeachable results.

Michael Knights, a senior fellow with The Washington Institute, has studied Gulf military affairs for over twenty years. Tim Michetti, managing director of TSM Consulting, has spent the past five years investigating illicit weapon flows throughout Africa and the Middle East.

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