A major new problem is brewing.
President Donald Trump’s growing economic pressure campaign against Iran is creating an unexpected challenge involving Turkey, a key NATO ally with deep strategic ties to the United States.
According to flight records reviewed by the Foundation for Defense of Democracies, at least 83 flights from Iranian airlines under U.S. sanctions arrived in Turkey in the five days after a key American sanctions deadline passed.
The findings are drawing attention to an important question for the Trump administration: How aggressively will Washington enforce its Iran sanctions when businesses operating inside an allied country continue providing access to targeted airlines?
The issue comes as Trump seeks both tougher economic restrictions on Tehran and closer cooperation with Turkish President Recep Tayyip Erdoğan.
That combination could make Turkey one of the most important tests yet of Washington’s broader effort to restrict Iran’s access to international aviation, banking and trade.
Trump Administration Expands Iran Sanctions
The latest dispute follows a major action by the U.S. Treasury Department on September 8.
Treasury designated all 27 remaining active Iranian airlines under Executive Order 13902 as part of the administration’s widening economic campaign against Tehran.
U.S. officials have accused Iran of using parts of its aviation sector to transport military personnel, weapons and other restricted cargo.
The sanctions are designed to make those operations more difficult by increasing the financial risks for foreign companies that provide Iranian carriers with fuel, airport services, maintenance, banking assistance or other commercial support.
Treasury has warned that foreign businesses dealing with sanctioned airlines could potentially lose access to important parts of the U.S. financial system.
That warning matters because international airlines depend heavily on foreign airports, financial institutions and service companies to maintain regular operations.
Washington’s strategy therefore goes beyond sanctioning the airlines themselves.
The administration is also trying to convince companies around the world that continuing to support those carriers could carry substantial financial consequences.
Dozens of Iranian Flights Continued Into Turkey
That strategy appeared to face a major challenge shortly after the sanctions deadline.
Researchers Ahmad Sharawi and Sinan Ciddi of the Foundation for Defense of Democracies reviewed Flightradar24 flight histories and reported that at least 83 flights operated by sanctioned Iranian airlines landed in Turkey between September 23 and September 27.
Those flights reportedly arrived in Istanbul, Ankara and Izmir.
The researchers found that 12 Iranian airlines under U.S. sanctions were among the carriers arriving in Turkey.
According to FDD, Iran Airtour and Caspian Airlines each recorded 12 landings, while Iran Air recorded 10.
ATA Airlines and AVA Airlines reportedly accounted for nine landings each.
Eight of the 12 carriers identified by researchers had been included in Treasury’s September 8 sanctions action.
The flight activity does not by itself prove that the Turkish government or individual Turkish companies violated American sanctions law.
However, it demonstrates one of the practical challenges facing the Trump administration as it tries to reduce Iran’s access to international transportation networks.
Treasury Warns Companies About Sanctions Risks
Treasury Secretary Scott Bessent previously warned companies about a September 23 deadline connected to continued support for sanctioned Iranian airlines.
Companies providing services such as fuel, banking assistance or airport support could expose themselves to U.S. sanctions, according to Treasury.
The administration hoped those warnings would persuade foreign businesses to distance themselves from Iran’s aviation industry.
The Treasury Department has since said American officials are discussing the issue directly with Turkish authorities.
A Treasury spokesperson said the department has continued conversations concerning Turkey’s aviation connections with Iran and has warned Turkish financial institutions and businesses about their possible sanctions exposure.
Treasury also pointed to earlier developments that officials said demonstrated progress, including the suspension of certain Mahan Air operations and action involving Iran-linked banking activity.
The administration says those efforts are part of a broader campaign known as Operation Economic Outcast, which seeks to restrict Iran’s access to international markets and sources of revenue.
Turkey Has Already Taken Some Action
Turkey has taken several steps to reduce aviation connections with Iran.
AJet, Turkish Airlines and Pegasus reportedly stopped listing flights to Iran on their schedules.
Mahan Air also suspended service to Turkey beginning September 21.
The changes suggest Ankara has responded to at least some of Washington’s concerns.
Mahan Air has been under U.S. sanctions since 2011.
The Treasury Department has accused the airline of providing financial and logistical support to Iran’s Islamic Revolutionary Guard Corps-Quds Force.
Despite those changes, other sanctioned Iranian airlines have reportedly continued operating flights into Turkey.
That has led analysts to question whether Washington will consider additional measures against companies that continue servicing those carriers.
Could Turkish Companies Face U.S. Sanctions?
FDD researcher Ahmad Sharawi has argued that Washington could place additional pressure on private companies that provide services to sanctioned Iranian airlines.
His comments represent the organization’s policy position rather than an announced decision by the Trump administration.
Sharawi argued that targeting companies supporting sanctioned carriers could make businesses more reluctant to continue providing services.
That could eventually make it harder for Iranian airlines to maintain international routes.
The effectiveness of the sanctions therefore may depend less on the airlines themselves and more on whether foreign companies decide that maintaining commercial relationships with them is worth the financial risk.
For the Trump administration, enforcement decisions involving Turkey could be especially sensitive because Ankara remains an important NATO partner.
Trump’s Relationship With Erdoğan Adds Another Layer
The sanctions dispute comes while Trump is pursuing closer relations with Turkish President Recep Tayyip Erdoğan.
Turkey has long played an important strategic role for the United States because of its NATO membership, military strength and geographic position between Europe and the Middle East.
Trump has publicly emphasized his relationship with Erdoğan and has discussed the possibility of restoring Turkey’s access to the advanced F-35 fighter jet program.
Turkey was removed from the program after purchasing Russia’s S-400 air-defense system.
That purchase also resulted in American sanctions beginning in 2020.
During a July 2026 visit to Turkey, Trump indicated that his administration was prepared to reconsider some restrictions and explore a possible path toward allowing Ankara to purchase F-35 aircraft.
However, existing congressional and legal restrictions connected to Turkey’s possession of the Russian S-400 system remain significant obstacles.
Erdoğan said in September that he expects Washington to take concrete steps regarding Turkey’s possible return to the program.
That means the United States and Turkey are simultaneously discussing major defense cooperation while facing disagreements over sanctions enforcement involving Iran.
NATO Relationship Could Complicate Enforcement
That puts Washington in a difficult diplomatic position.
The Trump administration wants foreign governments and businesses to take its Iran sanctions seriously.
At the same time, it has an interest in maintaining a strong working relationship with Turkey.
Turkey controls strategically important territory near the Black Sea, Middle East and eastern Mediterranean.
It also hosts important NATO military facilities and maintains one of the alliance’s largest armed forces.
Any significant sanctions dispute between Washington and Ankara could therefore extend well beyond commercial aviation.
For Trump, the challenge will be balancing the administration’s pressure on Iran with broader U.S. security interests involving Turkey.
Washington Says Economic Pressure Is Working
Treasury officials have argued that the administration’s broader strategy is already producing results.
The department says Iran has faced growing economic pressure as Washington and its international partners work to restrict access to banking networks, international aviation and energy markets.
Treasury has also continued announcing sanctions against individuals and companies accused of helping Iranian military procurement networks.
On September 29, the department announced another round of measures targeting individuals and entities that officials said were involved in obtaining weapons or components for Iran’s Ministry of Defense and Armed Forces Logistics.
U.S. officials say Iran relies heavily on international middlemen and commercial networks to acquire technology and materials used in military programs.
Washington’s strategy is aimed at disrupting those networks wherever they operate.
Attention Also Turns to Iran’s Shipping Network
Iran’s aviation industry is not the only focus of the administration’s economic campaign.
Concerns are also growing over Iranian-linked maritime activity in waters near Malaysia.
United Against Nuclear Iran, an advocacy organization that supports stronger economic pressure on Tehran, said investigators traveled approximately 100 nautical miles into the South China Sea and observed Iranian-linked tankers, cargo vessels and other ships operating near Malaysia’s Eastern Outer Port Limits.
The organization described the concentration of vessels as part of a network helping Iran continue international trade.
Those claims have not independently established that Malaysian companies or officials violated U.S. law.
UANI has called on Washington to consider sanctions against entities it believes are helping Iranian vessels continue operating.
Those recommendations remain advocacy positions rather than findings of legal wrongdoing by the U.S. government.
The allegations nevertheless highlight another challenge facing American sanctions policy.
Even when Washington restricts one route or business relationship, Iranian companies may attempt to rely on different ports, financial networks or transportation partners.
Sanctions Enforcement Becomes the Bigger Test
The continuing airline activity in Turkey illustrates why imposing sanctions and enforcing them are two different tasks.
The United States can prohibit American companies from doing business with targeted Iranian entities and threaten restrictions against foreign firms that provide certain types of assistance.
But the ultimate effectiveness of those measures depends heavily on international cooperation.
Companies must decide whether continued business with Iran is worth risking access to the much larger American financial system.
Foreign governments must also decide how closely they are willing to cooperate with Washington.
Turkey is particularly important because it is both an American security partner and a regional economic power with longstanding commercial relationships across the Middle East.
That makes the current aviation dispute far more complicated than a disagreement involving a country with limited ties to Washington.
What Happens Next Could Matter Beyond Turkey
The Trump administration now faces a decision that could influence how governments and businesses elsewhere interpret American sanctions.
If Washington aggressively targets companies servicing sanctioned Iranian airlines, other businesses may become more cautious about maintaining similar relationships.
If enforcement remains limited, critics could argue that sanctioned carriers still have important access points to international markets.
The administration has indicated that its economic pressure campaign will continue.
For Americans following national security and foreign policy, the Turkey dispute offers a revealing example of the challenges involved in enforcing sanctions across a complicated network of allies, businesses and international transportation systems.
Trump’s campaign against Iran is therefore becoming about more than simply placing additional companies on a sanctions list.
It is increasingly becoming a test of whether Washington can persuade allies and private businesses around the world to help enforce those restrictions.
And with Turkey simultaneously seeking closer defense cooperation with the United States, including renewed access to the F-35 program, the outcome could have consequences extending well beyond the 83 flights now attracting attention.
