<h1>US extraterritorial 25% tariff on imports tied to Iran business pressures partners; prompts China countermeasures and trade retaliation</h1> A new US policy threatens a 25% tariff on imports from any country 'doing business' with Iran, introducing an extraterritorial trade restriction and de facto secondary-sanctions mechanism; its operative effect is to expose trading partners to additional cumulative tariffs on US-bound trade, pressuring them to curtail oil and other commercial ties with Iran. China has signaled it will adopt countermeasures and defend its lawful rights; the operative effect is a diplomatic and potential trade-retaliation response that could escalate tariff disputes and prompt China to diversify energy sourcing and protect overseas investments.