In six-year first, regional rivals meet in effort to boost security cooperation, amid a spike in tensions in the Persian Gulf

FM Zarif claims increased tensions are 'due to America's economic terrorism and Europe's inability to fulfill its commitments'

HMS Montrose had 85 'interactions' with Iranian forces during recent 27-day patrol, though contacts have built a 'healthy understanding' on both sides, Royal Navy man reveals

40 images go on display at Tehran exhibit to throw spotlight on seizure of Islamic Republic's 'Grace 1,' denounced by supreme leader as UK 'piracy'

Ship leader claims UK forces boarded Grace 1 and made his unarmed crew kneel on deck at gunpoint; London says its troops acted in compliance with international norms

Request comes after London ordered navy to escort its ships through world's busiest oil shipping lane in response to Iranian soldiers seizing British tanker

Newly released radio communications show Revolutionary Guards warning British sailors on HMS Montrose not to put their 'life in danger' by interfering in capture of Stena Impero

London dispatches warship to Gulf to escort UK-flagged tankers across world's busiest oil shipping lane amid escalating tensions

At Vienna summit, deputy FM tells remaining signatories of ailing 2015 pact they 'must not create any obstacles' to Tehran's oil exports

Officials from crewmen's home countries have met with them as the Stena Impero remains held by Tehran, Stena Bulk says