China has warned that it will safeguard its interests after the United States widened sanctions against Iran, signalling resistance to Washington’s latest effort to increase pressure on Tehran and those that continue trading with it.

The United States has threatened to isolate countries that keep doing business with Iran. That warning has particular relevance for Beijing because Tehran sells much of its oil to China, making Chinese purchases an important part of Iran’s external trade.

The supplied report does not identify which US sanctions were expanded, when the additional measures take effect or what Washington means in practice by isolating countries that continue commercial relations with Tehran. It also does not provide details about any exemptions, enforcement steps or penalties that could apply.

China’s statement similarly leaves key questions unanswered. Beijing has said it will protect its interests, but the available evidence does not specify whether that could involve diplomatic action, changes to trading arrangements or another form of response.

For now, the development puts China’s purchases of Iranian oil under sharper attention as Washington seeks to discourage continued business with Tehran. The effect on oil flows, Chinese companies or the wider relationship among the three countries is not yet known from the information available.