Iran has effectively closed the Strait of Hormuz, and shutting down the Bab al-Mandeb Strait could further disrupt oil markets.

The threat from the president has left global markets in another period of uncertainty, with questions over how the blockade will be enforced

The U.S. naval blockade of the Strait of Hormuz threatens to halt more tanker traffic, sending oil surging and risks drawing China into a widening confrontation with Washington.

The U.S. blockade, set to begin at 10 a.m. ET, will apply to "any and all Ships trying to enter, or leave, the Strait of Hormuz," President Donald Trump said.

Trump says Beijing ‘would like to see this ended’ as the US moves to stop vessels transiting to and from Iranian ports.

Iran has effectively closed the Strait of Hormuz, and shutting down the Bab al-Mandeb Strait could further disrupt oil markets.