US sanctions Iran, Tehran threatens retaliation

The Trump administration has announced a new round of sanctions targeting Iran's economy, with the Treasury Secretary vowing to "tighten the noose" around Iranian revenue sources.

The administration has warned of an "economic D-Day" for countries that continue to trade with Tehran.

China has defended its cooperation with Iran and warned against efforts to disrupt it.

Analysts say repeated bombing campaigns have failed to change Iran's strategic calculus.