US threatens severe sanctions against countries with economic ties to Iran

Washington launches campaign to isolate Tehran but it is unclear whether it will apply measures to China

The US has threatened to impose severe sanctions against any country or entity maintaining economic ties with Iran, hoping to achieve with economic measures what military means have so far failed to do.

It is unclear, however, how far the Trump administration is prepared to go in confronting China, Iran's biggest trading partner, which has signalled its resistance to US economic pressure to cut off links with an ally.