Other weapons, such as an advanced drone the Houthis claim to have developed, may be able to cover the distance, but there's a second problem: the apparently sophisticated nature of the strike. A number of chemical processes are carried out at the site, but perhaps the most important is the separation of oil from highly flammable hydrogen-sulfide gas. That separation is done on-site using a series of custom-built "stabilization towers. But Hinz says it's likely that extensive U. Abqaiq is the linchpin of oil production for the Gulf nation, according to Joshua Shifrinson, an associate professor of international relations at Boston University who has conducted an extensive analysis. But Tabatabai notes that even if a proxy were involved, she believes such a large and complex strike would have required signoff at the highest levels by Iranian authorities. The question is how big that role might be. Iran has categorically denied any involvement in the attacks, calling such accusations "maximum lies," according to reports in Iranian state media. Iran almost certainly had some role in a major attack on an oil production facility in Saudi Arabia, according to independent analysts reviewing the available evidence.