China's foreign ministry warned on Tuesday it would impose "resolute countermeasures" if the United States follows through on threats to impose additional tariffs linked to allegations that Beijing is supplying weapons to Iran. US President Donald Trump said over the weekend he would impose a 50 per cent tariff on Chinese goods if China provided military assistance to Tehran, following media reports citing US intelligence assessments that Beijing may have already delivered shoulder-fired missiles and was preparing to send air defence systems to Iran. Beijing flatly denied the reports as "completely fabricated," while analysts note that although China is Iran's largest oil customer, the two countries have no formal military alliance and their relationship is largely viewed as transactional — a distinction that may complicate US efforts to use tariffs as leverage ahead of a planned Trump visit to Beijing next month.