From Noting to Enforcing: Turkey Shuts Iran's Banking Bridge on Its Own Authority
Turkey has moved from taking note of U.S. sanctions to enforcing them against Iran, and it has moved faster than its own rhetoric. In fifteen days Ankara shut the three Iranian channels that Washington named. The deposit-insurance fund took over Golden Global Bank, Mahan Air was told to end its Turkish flights from September 21, and on September 18 the banking regulator revoked the license of Bank Mellat's Istanbul branch, the Iranian state-linked bank that has settled Turkish-Iranian trade since 1982. The last and largest step came with no new U.S. designation behind it, and the decision text does not mention the United States. Bilateral trade stays open and Turkish statements on Iran have not changed. What has changed is the financial layer of the relationship, which in early September still looked like the weak point in Washington's economic campaign and is now being closed by Turkish regulators acting under Turkish law. We assess that Ankara is protecting its banks' access to dollar clearing, that the trade relationship survives with a weaker and more expensive payment system behind it, and that Tehran's answer is to move the visible relationship to the land border. A special assessment for September 19, 2026.