Following the imposition of new US sanctions on companies in Hong Kong and mainland China involved in Iran's oil trade, China has warned that it could retaliate. The Financial Times reports that a Chinese foreign ministry spokesperson stated that Beijing would take "all necessary measures" to protect its rights and interests, opposing what it described as unilateral sanctions not backed by international law or UN Security Council authorization. This warning comes ahead of an expected meeting between US President Donald Trump and Chinese President Xi Jinping next month to discuss trade issues. China is Iran's largest oil customer, with Chinese buyers accounting for about 90% of Iran's oil exports. While major state-owned refiners comply with US sanctions on Iranian crude, smaller private refiners continue to import and process it, some of which have been sanctioned by the US this year. Despite this, Beijing has instructed Chinese companies not to comply with such measures. The potential for broader US secondary sanctions comes at a sensitive point in US-China relations. China's message to Tehran is that it wants peace talks to continue, and Chinese officials have stepped up diplomatic contacts in the Middle East.