The latest incident in the Strait of Hormuz involving a British oil tanker and Royal Navy frigate comes at a particularly sensitive time as tensions continue to bubble between the US and Iran.
HMS Montrose had to intervene when three Iranian vessels impeded the route of the British Heritage tanker through the Strait.
Here, PA examines the background to the recent issues.
What has happened so far?
June 13: Two US oil tankers near the Strait of Hormuz were attacked in an assault that left one ablaze and adrift, with 44 sailors evacuated from both vessels. The US Navy rushed to assist, with American President Donald Trump blaming Iran for the incidents.
Iran denied involvement in the tanker attacks and accused America of promoting an “Iranophobic” campaign.
June 20: An American military drone worth 100 million US dollars (£78 million) was downed by Tehran, with Iran’s president Hassan Rouhani claiming it had violated their airspace.
The move marked a new high in the rising tensions between the two countries, as Iran’s naval commander warned his forces would not hesitate to down more US drones if they entered its airspace.
Mr Trump then pulled back from the brink of retaliatory military strikes on Iran after he was told 150 people could die. He has since signed an executive order targeting Iran’s supreme leader Ali Khamenei and his associates with financial sanctions.
July 4: Royal Marines from 42 Commando were involved in an operation to seize a supertanker off Gibraltar suspected of carrying oil destined for Bashar al-Assad’s Syrian regime. They boarded the ship by descending on ropes from a Wildcat helicopter and by using rigid inflatable boats.
They worked alongside authorities in Gibraltar to detain the Iranian tanker Grace 1, which was believed to be heading to the Banyas refinery in breach of European Union sanctions. In response, Iran’s revolutionary guard warned a British oil tanker could be seized in retaliation.
July 10: Royal Navy frigate HMS Montrose drove off three Iranian vessels which tried to stop the commercial ship British Heritage.
It is understood the tanker was making passage out of the Gulf through the Strait of Hormuz when the ship was approached by the Iranian vessels. HMS Montrose was nearby and proceeded to come in between.
Warnings were given but no shots were fired. The Iranian vessels then turned around and left.
What is the situation as it stands?
Tensions between the United States and Iran have ratcheted up several notches in recent weeks, with Washington dispatching warships and bombers around the Persian Gulf, and Tehran announcing it would break uranium stockpile and enrichment limits set by its nuclear deal with world powers.
These increased strains come a year after Mr Trump withdrew from Iran’s 2015 nuclear accord with world powers and restored crippling sanctions. In turn, this prompted Iran to say it would not negotiate another deal with Washington.
Foreign Secretary and Tory leadership hopeful Jeremy Hunt has previously said Britain is urging all sides in the dispute to “de-escalate” in order to avoid a slide into armed conflict, but he said the UK would consider joining the US in military action.
Why is the Strait so important?
Its size belies its importance as one of the most strategic waterways in the world, linking the Middle East’s crude oil producers with key markets around the globe.
The Strait falls between the southern coast of Iran and the most northerly tip of Oman, a distance of around 20 miles at these pinch-points.
It has two shipping lanes, each around two miles wide. Between one-fifth and one-sixth of the world’s oil moves through the strait – around 17 million barrels per day – a significant quantity of the valuable commodity.
Any impasse on oil leaving the Strait could have wide-ranging consequences – including soaring prices and disruption to world supplies.
Will British troops be sent to the region?
At the moment, no. There are already an undisclosed number of British service personnel in the Middle East, predominantly from the Royal Navy. There is a joint base at Ducm in Oman, with a Combined Maritime Forces base in Manama, Bahrain.
HMS Montrose has been in the region since April as part of a three-year deployment supporting counter-terror and anti-smuggling work. The Royal Navy has had a presence in the region for more than 30 years following the Iran-Iraq war in 1980 in what is known as Operation Kipion.
Ships from both the Royal Navy and Royal Fleet Auxiliary have been on patrol in the Gulf for 24 hours a day, seven days a week and 365 days a year, according to the Royal Navy.