US President Donald Trump announced a naval blockade on the Strait of Hormuz targeting ships paying Iran.
The decision followed failed US-Iran talks in Islamabad.
JD Vance confirmed negotiations ended without a deal.
Trump said the blockade starts immediately and includes interceptions in international waters.
He ordered the US Navy to carry out the operations.
He added that other countries will join the effort.
He stressed the US will not allow Iran to profit from shipping fees.
He confirmed US forces are on full alert.
He warned of further escalation if tensions continue.
The Strait of Hormuz is a key global energy route.
Observers fear impacts on global markets.
