The new head of Iran’s Supreme National Security Council on Sunday said Tehran plans to announce an “exclusion zone” outside the Strait of Hormuz aimed at vessels it believes are attempting to transit the waterway.

Mohsen Rezaei’s comments to Iran’s state broadcaster came with few details, a day after the U.S. struck three Iranian oil tankers in response to Tehran launching ballistic missiles at U.S. warships. Experts called the launches a dangerous escalation after Iran’s previous attacks at sea targeted commercial shipping.

The new zone should be announced in the coming days and weeks and “will begin from the line of the U.S. naval blockade, extend toward the Strait of Hormuz, and from this side continue into the Persian Gulf,” Rezaei said. “Any ship that enters this area with the intention of passing through the Strait of Hormuz and is identified will be placed on our sanctions list.”