First it was Iran imposing a de facto blockade strangling the Strait of Hormuz and a fifth of the world's oil trade.

This week, the United States followed suit - imposing its own blockade after calls for naval assistance fell on deaf ears among world leaders.

The U.S. Central Command says no vessels have made it past U.S. naval forces during the first 48 hours of the blockade, but ship tracking data suggests several Iranian-linked vessels have travelled through the Strait since the US blockade began.

• GUEST: Arsenio Dominguez, Secretary General of the International Maritime Organization
• PRODUCER: Pip Cook