IRAN has reportedly test fired a ballistic missile as tensions continue to escalate in the Gulf.

The Shahab-3 missile travelled 1,000km, but did not pose a threat to shipping or US bases, according to a Pentagon official.

11 Iran Revolutionary Guards fire a Shahab-3 long-range ballistic missile in 2006 (file) Credit: AFP

Iran is believed to have tested the medium-range missile on Wednesday in a bid to improve the "range and accuracy" of its weapons.

News of the provocation emerged after Boris Johnson ordered the Royal Navy to accompany all British-flagged ships through the Strait of Hormuz.

This ramping up of the navy's protection mission by Boris Johnson comes in the wake of Iran seizing Brit tanker the Stena Impero.

It marks a dramatic escalation of the crisis with Iran following weeks of heightened tensions in the region.

11 HMS Montrose is patrolling in the Gulf and is to step up protection of UK shipping Credit: Reuters

11 A woman and boy walk past Shahab-2 (L) and Shahab-3 missiles on display in Tehran in 2008 (file) Credit: AFP - Getty

Tensions soared following Donald Trump's decision last year to withdraw from the nuclear deal and impose maximal sanctions on Iran.

In the past few weeks, Iran has shot down a US spy drone and six oil tankers have been sabotaged near the strait.

The US has downed at least one Iranian drone after the USS Boxer took "defensive action" last Thursday – and a second Iranian drone may have been destroyed.

Iran possesses the largest and most diverse missile arsenal in the Middle East, according to the CSIS missile defence project.

IRAN'S MISSILE ARSENAL

While Iran has not yet tested or deployed a missile capable of striking the US, it continues to hone longer-range missile technologies.

The country has short and medium-range ballistic and cruise missiles capable of striking as far as Israel and southeast Europe.

Iran has also become a centre for missile proliferation, supplying proxies such as Hezbollah and Syria’s al-Assad regime with a steady supply of missiles and rockets.

According to the Military Balance, Iran has 32 batteries of Russian-made S-300 ground-to-air missiles that have been delivered by Moscow since 2016.

They are seen as posing a serious threat.

The Islamic Republic has also developed Iranian versions of these missile systems, including the Bavar 373, SAM Tabas and SAM Raad which are regularly displayed at military parades.

The Revolutionary Guards claim that they shot down the US drone with a Khordad 3 missile, a version of the SAM Raad.

11 Iran possesses the largest and most diverse missile arsenal in the Middle East, according to the CSIS missile defence project

READY TO BLOW Iran's nuke program IRAN’S nuclear capabilities have been the subject of concern and debate for more than two decades. Iran's Supreme Leader Ayatollah Khamenei has repeatedly denied Iran is building a bomb and says weapons of mass destruction are forbidden under Islam. But its enrichment of uranium and history of deception created deep mistrust. After more than two years of negotiations and threats to bomb the country’s facilities, Iran and world powers agreed in 2015 to settle the dispute. The deal set limits on the Islamic Republic’s nuclear work in exchange for relief from economic sanctions that had crimped oil exports and hobbled its economy. Then in May 2018, Donald Trump announced the US was abandoning the pact negotiated under his predecessor and would reinstate sanctions. Little more than a year later, Iran responded by violating its limits on uranium enrichment. A think tank believes Tehran's nuke scientists are ready to massively step up uranium enrichment at the heavily-fortified Fordow Plant.

11 Iran's nuclear enrichment site at Fordow has two rings of steel around it, and is buried deep within a rural mountain for protection

BOJO'S PROTECTION PLAN

The navy currently has HMS Montrose deployed in the Strait of Hormuz and it has reportedly already carried out the first escort under the new protection plan.

Another surface ship, HMS Duncan, a nuclear powered submarine and Royal Marine Commandos could also be sent to bolster the UK presence.

"The Royal Navy has been tasked to accompany British-flagged ships through the Strait of Hormuz, either individually or in groups, should sufficient notice be given of their passage," said a government spokesman.

"Freedom of navigation is crucial for the global trading system and world economy, and we will do all we can to defend it."

The move came just hours after new Prime Minister Boris Johnson took office.

Mr Johnson is close to Donald Trump, who has deployed a large military presence in the Gulf in response to what the US said were Iranian threats.

The current tension between Iran and the UK began when Royal Marines seized an Iranian tanker at the request of the US.

The Grace 1 is currently detained in Gibraltar amid suspicion it was taking oil to Syria in violation of EU sanctions.

CONVOYS

Under the new Royal Navy escort mission, UK-flagged ships have been told to give the Department of Transport sufficient notice of their travel plans in the area, Sky News reports.

Ships might be grouped together in convoys or accompanied individually depending upon how many are travelling on a given day, according to sources.

Britain has been seeking to put together a European-led maritime protection mission to ensure safe shipping through the Strait of Hormuz.

On Friday, the Revolutionary Guard launched a gunboat and helicopter raid on Stena Impero, which is registered in the UK, claiming it had turned off its tracker and ignored warnings.

Iran's seizure of the tanker was described as an "state piracy" by the government.

Another vessel, the Mesdar, was also intercepted and forced towards Iranian territory in what appeared to be a co-ordinated strike.

State TV footage shows Iranian armed forces on board the Stena Impero after it was seized in the Strait of Hormuz.

The clip is thought to have been filmed in the southern port of Bandar Abbas, where jet boats have been sailing around the British ship.

'STATE PIRACY'

Iranian special forces stormed the ship by abseiling down from a helicopter.

Startling images have emerged of the ship being circled by a military speedboat.

Britain has demanded Iran release the tanker and in response the Islamic Republic has offered to swap the vessel for the Grace 1.

Iran had warned the UK that the seizure would not go "unanswered" and has also issued a chilling warning that it was using drones to track every ship in the Gulf.

In a thinly veiled threat the Revolutionary Guard said there “world leading drones” were following “all enemy ships” and taking pictures “point-by-point from their origin until the moment they enter the region”. It has also emerged Tehran wants to impose a "toll" on all ships passing through the Strait of Hormuz, saying it would be used to "protect" the safety of the vessels.

Mohammad Javad Zarif, the Iranian foreign minister, has insisted his country doesn't want confrontation.

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"It is very important for Boris Johnson as he enters 10 Downing Street to understand that Iran does not seek confrontation, that Iran wants normal relations based on mutual respect," he said.

Fears have recently been raised that the Royal Navy lacks the strength to conduct missions to protect UK shipping.

Since the Falklands War, the navy has dropped from 80 vessels to 50 but with ten of those currently out of action for maintenance.

11 The Iranian flag was hoisted over seized British tanker Stena Impero Credit: PressTV

11 An Iranian Revolutionary Guard jet boat sails around the seized British-flagged tanker Stena Impero in Bandar Abbas Credit: EPA

11 Hatching plan . . at 4pm, IRG special forces on board a chopper inspect the Stena Impero, en route to Saudia Arabia with its 23 crew

11 The armed troops prime their weapons and make final checks as they prepare to storm the British oil tanker below

11 Soldiers abseil from a hovering helicopter while gunboats surrounding the Impero force it north towards Bandar Abbas Credit: AFP or licensors

HMS Montrose accompanies two merchant vessels in the Gulf

11

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