US secondary sanctions on Iran are rapidly translating into real-world pressure.

After the September 23 deadline passed, multiple Gulf neighbors including the United Arab Emirates and Oman suspended entry for Iran Air flights — the first major practical impact of Washington extending its sanctions reach to third-country companies.

At the same time, Saudi Arabia announced it intercepted six ballistic missiles launched by Yemen's Houthi rebels, as a new front in the Middle East conflict continues to heat up. Together, these developments are accelerating Iran's dual isolation in aviation and the economy.

A pre-announced "air blockade"

The US Treasury's September 23 deadline has now passed. From that day forward, any foreign company providing fuel, ground handling services, or ticket sales to Iranian airlines will be cut off from the US dollar financial system.

US Treasury Secretary Scott Bessent put it bluntly in an interview: "All Iranian airlines will be grounded globally. If any airport, fuel supplier, ground handling company, or ticketing agency continues to provide services to Iranian aviation operators, they will lose access to the US dollar financial system due to US secondary sanctions."

The US Treasury had previously placed nearly 30 Iranian airlines on its sanctions list, including agents of Mahan Air, Iran's largest private airline, as well as 27 smaller carriers. The US justification is that Iran uses civil aviation flights to transport weapons and fighters, and Mahan Air is alleged to have ties to Iran's Islamic Revolutionary Guard Corps.

This sanctions strategy was dubbed "Economic D-Day" by Trump himself, who compared it to the Allied invasion of Nazi-controlled France during World War II. Yet unlike a military operation, the weapon in this "D-Day" is the dollar clearing channel, and the target is every company worldwide that does business with Iran's aviation industry.

Gulf neighbors lead enforcement: UAE, Oman close airspace

Less than 24 hours after the sanctions took effect, Iran's neighbors began to act. On September 24, the UAE General Civil Aviation Authority issued a statement announcing the suspension of all Iranian airline flights to and from the UAE starting that day until further notice. The statement explicitly stated the decision was "based on US sanctions imposed on Iranian airlines."

The UAE is the Middle East's largest aviation hub, and Dubai International Airport has long been a critical transit point for Iranian passengers and cargo traveling to and from the rest of the world. Cutting this route deals a direct blow to Iran's external connectivity.

Oman did not hesitate either. According to Iran's Tasnim News Agency, flights to Oman, Georgia, Azerbaijan, and Baghdad, Iraq, have all been suspended. Iran's Civil Aviation Organization announced that flights from Tehran to Baghdad and Muscat were canceled starting at midnight on September 23, with authorities attempting to reroute some flights to the Iraqi Shiite holy city of Najaf.

Georgia had already moved first, announcing on September 22 that it would stop accepting Iranian airline flights. On the Turkish side, Mahan Air has also suspended flights from Tehran to Istanbul and Ankara.

The flight schedule published Thursday at Tehran's Imam Khomeini Airport shows that flights to and from Afghanistan, China, Iraq, and Turkey are still operating, but flights to and from neighboring Gulf states have disappeared from the board. For Iran, which has long relied on Gulf states as its commercial and travel gateway, this "selective suspension" means its aviation network is being gradually compressed to a handful of destinations still willing to bear US pressure.

Iran's response and the daily reality of an "open-air prison"

Iran has not been sitting idle. A senior Iranian official threatened that if regional countries comply with the US ban, Iran will ensure their airports "cannot be used." This is not an empty threat — Iran possesses a large arsenal of ballistic missiles and drones and has repeatedly demonstrated its ability to strike regional targets.

But threats cannot change one fact: Iran's aviation network is visibly shrinking. A retired teacher in Tehran said: "We are living in an open-air prison." This captures the true cost of sanctions — it falls not on the abstract "aviation industry" but on every ordinary person who needs to travel abroad for medical treatment, to visit family, or to do business.

Iranian airlines have long been tasked with transporting medicines, auto parts, and other critical supplies, while also serving as the core channel for Iranians traveling abroad. Matthew Levitt, a senior fellow at the Washington-based Washington Institute for Near East Policy, told The Wall Street Journal that if the world truly cooperates with the sanctions, "Iranian airlines will be reduced to airlines operating only domestic routes."

Iran's economy is already under immense pressure. The national currency, the rial, fell to a historic low in August, surpassing 2 million to the dollar, with domestic inflation running at 66%. Iranian President Pezeshkian previously acknowledged that comprehensive US sanctions and a maritime blockade have caused the country's foreign trade volume to plummet by about 35%. With sea lanes already blocked and air corridors now closing, Iran is transforming from a "sanctioned state" into a "besieged state."

Yemen front escalates in parallel: missiles, displacement, and the Red Sea crisis

Just as Gulf states were busy closing their airspace, the war in Yemen was intensifying in another direction, adding geopolitical pressure on Iran. On September 24, the Saudi-led multinational coalition announced it had intercepted and destroyed six ballistic missiles launched by the Houthis, with targets including the Saudi cities of Taif and Yanbu.

The Houthis claimed they launched attacks that day on a "sensitive target" in Riyadh, Saudi Aramco facilities in Yanbu, and multiple military targets in the Jizan region, using ballistic missiles, cruise missiles, and drones. Since declaring a blockade on Saudi Arabia in July, the Houthis launched another offensive this month against the Saudi-backed Yemeni government, while Saudi air forces conducted hundreds of airstrikes on Yemen.

After seizing Yemen's entire Red Sea coastline, the Houthis are advancing near Taiz and along the road to Aden. The Houthis claim that since the current escalation began, Saudi attacks on Houthi-controlled areas have totaled 1,018.

The humanitarian cost is climbing sharply. UN data shows that the latest escalation in Yemen has killed nearly 700 people, injured thousands, and displaced more than 125,000 internally, while thousands more risk crossing the Bab el-Mandeb Strait by boat to reach Djibouti and Somalia in Africa.

Armen Yadegarian, the UNHCR representative in Yemen, said that in just one to two weeks, more than 125,000 people were forced to flee their homes, most of them women, children, and the elderly.

The limits of sanctions: who enforces, who watches

The core logic of this "Economic D-Day" is that the US not only refuses to do business with Iran itself but also decides whether the rest of the world can do business with Iran. But this logic is facing a real-world test.

Chinese Foreign Ministry spokesperson Guo Jiakun stated clearly that China "consistently opposes illegal unilateral sanctions that lack a basis in international law and are not authorized by the UN Security Council." Russia has likewise refused to cooperate with the sanctions.

Notably, with a summit between Chinese and US leaders approaching, this divergence adds a diplomatic variable to Washington's sanctions enforcement. However, for most countries and companies, the allure of dollar clearing channels far outweighs the benefits of doing business with Iran.

The UAE's choice is telling — this Gulf state, which has deep commercial ties with Iran, ultimately chose to comply with US sanctions requirements. When even a hub like Dubai, with decades of trade ties to Iran, chooses to close its doors, the prospect of Iran's aviation industry being reduced to "domestic-only routes" is no longer just an analyst's assumption.

Editor's summary

The US expansion of sanctions tools from targeting Iranian entities to third-country service providers marks a qualitative shift in its economic pressure strategy against Iran. Unlike traditional asset freezes or trade bans, the operating logic of secondary sanctions is to force global companies to choose between the US market and Iranian business.

The speed of enforcement in aviation was unexpected — just one day after the sanctions took effect, the UAE and Oman closed their airspace, cutting off Iran's most important external air corridor. But the effects of sanctions have clear limits. China and Russia refuse to cooperate, and some of Mahan Air's Asian routes are still operating.

The essence of the sanctions is not a "global grounding" but rather pushing Iran's aviation network from the core of the global system to its periphery — retaining a few destinations not constrained by the dollar system while losing almost all short-haul regional connections.

Running parallel to the aviation blockade is the escalation in Yemen. Houthi attacks on Saudi oil facilities and large-scale Saudi airstrikes have formed a new front line, and the figure of over 125,000 Yemenis displaced shows that the cost of this war is being borne by the most vulnerable.

Two fronts — economic sanctions and military conflict — are applying pressure simultaneously within the same window, constituting a multi-dimensional squeeze on Iran and its regional allies. The next phase will depend on Iran's threshold of endurance under the dual pressure of the aviation blockade and the Yemen battlefield, and whether key external powers like China and Russia are willing to provide substantive economic relief for Iran.

Frequently asked questions

Q1: What are "secondary sanctions"? How do they differ from ordinary sanctions?

Ordinary sanctions target the target country itself — for example, prohibiting US companies from trading with Iranian firms. Secondary sanctions expand the scope to companies and individuals in third countries: even if you are not a US company, as long as you do business with Iranian airlines, the US can impose sanctions on you, with the core measure being exclusion from the dollar financial system. This means you cannot conduct any international trade settlement involving US dollars. This practice is controversial under international law because it effectively applies US domestic law to global companies.

Q2: Why would Gulf states like the UAE cooperate with US sanctions on Iran?

The UAE has deep commercial and geopolitical ties with Iran, and Dubai has long been an important transit point for Iran to trade around sanctions. But the UAE is also a key US security partner in the Middle East, and its aviation, finance, and energy exports are highly dependent on the dollar system and the US market. With the US explicitly threatening to "kick out of the dollar system" companies that violate the rules, the UAE faces a choice: keep Iran routes or keep access to the world's largest financial system. The UAE's choice shows that under the current level of sanctions pressure, the appeal of the dollar system outweighs the value of maintaining aviation links with Iran.

Q3: Iran threatens to make neighboring countries' airports "unusable" — what does this mean?

This is a signal of military escalation from Iran. Iran possesses large numbers of short- and medium-range ballistic missiles and drones and has previously attacked Saudi oil facilities and Israeli targets multiple times. If Iran follows through on its threat, it would mean the regional conflict escalating from a proxy war in Yemen to direct Iranian military strikes on Gulf state infrastructure. But the effectiveness of such threats is questionable: Iran is already under pressure on multiple fronts, and opening a new direct military confrontation could lead to further tightening of its economic blockade and even trigger a larger-scale military response.

Q4: How do the sanctions affect the daily lives of ordinary Iranians?

The impact is direct and wide-ranging. Iranian airlines are responsible for transporting imported medicines and auto parts, and the suspension of flights means supply chains for these goods will tighten further. At the same time, ordinary Iranians' channels for traveling abroad for medical treatment, visiting family, or business trips have been significantly narrowed. Iran's currency has fallen to a historic low, inflation is at 66%, and foreign trade has plummeted by about 35%. The aviation blockade, combined with the existing maritime blockade, is pushing Iran's economy from "sanctioned" further toward "besieged," with shortages and rising prices hitting ordinary families first.

Q5: What is the connection between the Yemen war and sanctions on Iran?

The Houthis are an important regional ally of Iran in Yemen, and their military actions are closely bound to Iran's strategic interests. While Iran itself faces an aviation blockade and economic sanctions, Houthi attacks on Saudi oil facilities and military targets constitute Iran's "proxy counterattack" — increasing America's political costs by striking its Gulf allies. The humanitarian cost of the Yemen battlefield — over 700 dead and more than 125,000 displaced — is the most direct human price of this proxy conflict, and Red Sea shipping security faces continued threats, with potential impacts on global energy trade that cannot be ignored.