The move tightens sanctions pressure on Iran's aviation sector at a time when the broader Iran conflict has already driven sustained volatility in oil markets, and it reinforces the Trump administration's wider economic squeeze on Tehran rather than introducing a new standalone shock. For oil specifically, the airline measures are unlikely to have a direct supply impact, but they signal continued escalation in the sanctions regime, which traders may read as reducing the likelihood of near term de-escalation and a fading war premium. The China angle is arguably more market relevant: Bessent's description of Chinese officials as "very engaged" on compliance, ahead of Thursday's Trump-Xi summit, could be read either as a genuine diplomatic opening or as pressure tactic framing before high level talks, and markets may look for further signals from that meeting on the broader US-China-Iran dynamic.---Washington is threatening to ground every Iranian airline worldwide by cutting off anyone who services them from the dollar system, starting tomorrow.Summary:US Treasury Secretary Scott Bessent told CNBC on Monday that all Iranian airlines will be shut down worldwide starting September 23.Bessent said any airport, fuel supplier or ticketing company that services a landed Iranian airline risks being cut off from the US dollar financial system.The move follows Treasury sanctions imposed earlier this month on all 27 remaining Iranian airlines that had not previously been sanctioned.In response, Turkey said it will no longer accept Iranian planes at its airports.Bessent said Chinese officials, including People's Bank of China Governor Pan Gongsheng, have been "very engaged" in discussions on compliance with US sanctions on Iran, following his weekend talks with Chinese Vice Premier He Lifeng ahead of Thursday's Trump-Xi summit.Bessent said he could not predict when the broader US-Iran conflict, ongoing since late February, would come to an end.US Treasury Secretary Scott Bessent said Monday that all Iranian airlines will be shut down worldwide starting September 23, as the Trump administration escalates its sanctions campaign against Tehran. Speaking to CNBC, Bessent said any airport, fuel supplier, or ticketing company that services an Iranian airline once it lands will risk being cut off from the US dollar financial system, effectively threatening to isolate Iranian carriers from the infrastructure needed to operate internationally.The warning follows Treasury sanctions imposed earlier this month on all 27 remaining Iranian airlines that had not yet faced such penalties, closing what had been a partial gap in the sanctions regime covering Iran's aviation sector. Bessent framed the latest step as a clear warning to any party still doing business with Iran's remaining carriers, saying they now risk exclusion from the global financial system. In an early response, Turkey said it will no longer accept Iranian aircraft at its airports, a move that reflects the kind of secondary compliance the sanctions are designed to compel. Iran's aviation sector has for years struggled under sanctions restricting its access to aircraft, spare parts, and maintenance services, and one major Iranian carrier had already suspended flights to Oman and Turkey ahead of Bessent's announcement.Bessent's comments came a day after he concluded talks with Chinese Vice Premier He Lifeng, in discussions he described as laying the groundwork for President Trump's summit with Chinese leader Xi Jinping later this week. He said Chinese officials, including People's Bank of China Governor Pan Gongsheng, have been "very engaged" in discussions around compliance with US sanctions on Iran, a notable characterisation given China's status as one of Iran's most significant remaining economic partners and diplomatic backers. Bessent did not elaborate on what form that engagement has taken or whether it extends to concrete commitments.Asked separately about the broader trajectory of the conflict, which has run since late February when US and Israeli strikes killed Iran's supreme leader and senior military officials, Bessent said he could not predict when it would end. The war has already reshaped global energy markets, with Iran responding to the initial strikes by disrupting the Strait of Hormuz, a critical waterway for oil transit, sending crude prices sharply higher as the conflict widened across the Middle East. The aviation sanctions add a further dimension to Washington's economic pressure campaign, which Bessent has previously described in terms of pushing toward what he called an "economic D-Day" for Iran, as the administration continues to combine military and financial pressure aimed at Tehran. This article was written by Eamonn Sheridan at investinglive.com.