What Happened: The United Kingdom denounced Iran's seizure of a British-flagged oil tanker in the Persian Gulf as a "hostile act" on July 20, Reuters reported. Meanwhile, Iran's Islamic Revolutionary Guards Corps posted a video online showing masked troops capturing the tanker, named the Stena Impero, on July 19.
Why It Matters: The West views the tanker's seizure in the strategic Strait of Hormuz as a major escalation after months of confrontation between the United States and Iran that has already taken the two nations to the brink of war. Iranian forces also forced another oil tanker, the Mesdar, to divert toward Iran on July 19, but later allowed it to continue on its way.
Background: Iran has threatened to retaliate for the United Kingdom's seizure of an Iranian supertanker near Gibraltar on July 4, accused of violating sanctions on Syria. A spokesman for Iran's Guardian Council said on July 20 that his country's seizure of the Stena Impero was in response to Britain's role in impounding the Iranian tanker.