A Royal Navy warship has arrived in the Persian Gulf to accompany British-flagged ships passing through the Strait of Hormuz, amid tensions after Iran seized a British tanker this month, The Associated Press reported.

The UK Ministry of Defense said Sunday that the HMS Duncan will join the Frigate HMS Montrose in the Gulf to defend freedom of navigation.

Defense Secretary Ben Wallace said the Royal Navy will escort UK vessels until a diplomatic resolution is found to secure the route again.

British tanker Stena Impero was seized last week in the Strait of Hormuz, by the Iranian Revolutionary Guard.

Iran said the ship was “violating international maritime rules.”