TEHRAN, Iran (AP) — Iran’s seizure of a British oil tanker was a response to Britain’s role in impounding an Iranian supertanker first, senior officials said Saturday, as newly released video of the incident showed Iranian commandos in black ski masks and fatigues rappelling from a helicopter onto the vessel in the strategic Strait of Hormuz.

The seizure prompted condemnation from the U.K. and its European allies as they continue to call for a de-escalation of tensions in the critical waterway.

U.K. Foreign Secretary Jeremy Hunt said Britain’s response “will be considered but robust.”

In comments on Twitter on Saturday, he said he spoke with Iran’s foreign minister and expressed extreme disappointment that the Iranian diplomat had assured him Iran wanted to de-escalate the situation but “they have behaved in the opposite way.”

He wrote: “This has (to) be about actions not words if we are to find a way through. British shipping must & will be protected.”

The free flow of traffic through the Strait of Hormuz is of international importance because one-fifth of all global crude exports passes through the waterway from Mideast exporters to countries around the world.

The narrow waterway sits between Iran and Oman.

The British-flagged Stena Impero was intercepted late Friday by Iran’s powerful Revolutionary Guard forces.