Washington: The US military on Thursday released a video it said showed Iran's Revolutionary Guard removing an unexploded mine from the side of one of the two oil tankers attacked near the Persian Gulf earlier in the day, as well as a photograph showing the apparent mine before its removal.

"At 4.10 p.m. local time an IRGC Gashti Class patrol boat approached the M/T Kokuka Courageous and was observed and recorded removing the unexploded limpet mine from the M/T Kokuka Courageous (video attached)," Navy Captain Bill Urban, a spokesman for the US military's Central Command, said in a statement.

The release of the video followed US Secretary of State Mike Pompeo's assertion that the US held Iran responsible for attacks, casting it as the latest in a series of "provocative actions" that have sharply raised tensions in the region.

A US assessment of Iran's responsibility, which forced the evacuation of the crews in international waters, was based in part on intelligence as well as the expertise needed to carry out the operation, Pompeo told reporters in Washington.