The series of provocations in the Gulf by the Islamic Republic of Iran, beginning with the sabotage of four vessels in mid-May, culminated last Friday in the illegal seizure by the Iranian Revolutionary Guard Corps Navy (IRGCN) of the British-flagged and operated Stena Impero oil tanker, followed shortly thereafter by the seizure of the Liberian-flagged, British operated MV Mesdar in the Strait of Hormuz. Only the Mesdar has been released. This episode has served to demonstrate the serious defence issues confronting Boris Johnson, the incoming United Kingdom (UK) Prime Minister, which have to be dealt with immediately and cannot be pushed off into the future when the domestic turbulence over Brexit has abated.

The problem set from Iran is clear. First, the clerical regime’s consistent defiance of the rules-based international order. Second, Iran’s challenge to both the US and the UK in the region, aiming to use low-risk, sub-threshold military means, including the use of unmanned aircraft system (UAS) technology and “deniable” proxies, to dismantle the Western security architecture in the Middle East. And third, the UK and the US will need to divert significant military resources to counter this sub-threshold threat.

Over the last two months, Iran has pursued a strategy of destabilisation in the Gulf, particularly in the narrow Strait of Hormuz – only 13 miles wide at its narrowest point. Utilising proxy actors directed by its Islamic Revolutionary Guards Corps (IRGC), Tehran has repeatedly fired ballistic missiles at the Saudi capital from Yemen , attacked Saudi-owned oil tankers off the coast of the United Arab Emirates at Fujairah with mines, and sabotaged the Marshall Islands-flagged Front Altair and Panama-flagged Kokuka Courageous  oil tankers in the international waters of the Gulf of Oman, among other things.

Following these alarming incidents, on 4 July, an Iranian ship, the Grace 1, was detained at the behest of the Gibraltese government by British Royal Marines on suspicion of smuggling Iranian oil to Syria, a violation of the European Union (EU) sanctions against Bashar al-Assad’s murderous regime, which is Iran’s only state ally in the region. The subsequent official Iranian response was, even by Tehran’s standards, quite something, first warning of ‘consequences’ to British interests in the region, accusing the UK of piracy, and then seizing these two vessels on 19 July.

It is worth noting that before Iran’s successful hijacking of British ships, there was an effort within one week of the Grace 1’s detention to capture the British Heritage tanker in the Strait of Hormuz. Fortunately, HMS Montrose was performing maritime escort duties and positioned itself between the Heritage and three small IRGCN vessels, training its 30mm guns on them whilst issuing a verbal warning to withdraw, which they did. The tried and tested IRGCN method of swarming much larger vessels with multiple smaller, more agile armed speedboats designed to out-maneuverer the larger frigates acting as escorts failed on that occasion, before bearing success last week.

According to UK Foreign Secretary Jeremey Hunt the Stena Impero was approached by five small Iranian vessels and a helicopter. Tehran has maintained that it took the Stena Impero because the ship was ‘violating international maritime rules’. Iran even claimed it only detained the Mesdar briefly to give it notice to comply with “environmental regulations”. This pretence to be enforcing, rather than trampling, the most basic customary international law will not wash. The UK Foreign Office and independent maritime traffic bodies have verified that Stena Impero was in international waters when it was compelled to change course and surrender to Iranian custody, an illegal act under both UK civil law and the United Nations Convention on the Law of the Sea (UNCLOS). Not even a week earlier Iran had done the exact same thing to the U.A.E.-based Riah oil tanker.

To say that this action could set a dangerous precedent would be to forego Iran’s repeated defiance of international law stretching a period of 40 years, but in the context of maritime security this is the most blatant example of Tehran’s recent willingness to disregard regional security practices in pursuit of its own agenda. Namely, by putting pressure on the West to maintain and indeed strengthen the failing JCPOA back into Iran’s favourable outcome; sanctions relief from the US.

The tensions of the last few months are usually ascribed to the US having pulled out of the ineffective Joint Comprehensive Plan of Action (JCPOA), the nuclear deal, in May 2018. President Donald Trump re-imposed economic sanctions, particularly on the energy sector in a bid to drive Iran’s oil exports to zero. True, neither Iran nor the European and Russian signatories to the JCPOA have abandoned the agreement, and the Europeans are trying to help Iran find workarounds to US sanctions, even as Tehran tests the tolerance of the other states by breaching the limitations on its enriched uranium stockpile and threatens to restart deactivated centrifuges that would allow it to produce stockpiles of high-enriched uranium, at 20% purity, far above the current stockpiles of 3.67%. But, so goes the argument, the severe economic strain is what has led to Iran to act out in an effort, first, simply to inflict retribution, and second and more important to create a political situation in which the US is compelled to return to the JCPOA directly, including its sanctions-relief provisions, or to at least avoid activating the “snap-back” sanctions mechanism at the United Nations Security Council that would entirely destroy the JCPOA and prevent a post-Trump President taking it back up.

Undoubtedly such considerations have played a part in Iran’s recent behaviour, but it should be borne in mind that the JCPOA was no kind of restraint on the clerical regime—and was never sold as such. President Barack Obama argued that the nuclear agreement’s achievement was to ensure Iran did not have a nuclear umbrella for its malign activities in the region. It was after the JCPOA was signed that Iran collaborated with Russia in a massive escalation in Syria to save Assad, for example. There is also precious little evidence that the sanctions are biting in a policy-meaningful way—as Iran’s increasing tempo of provocations attests.

Moreover, though the theocracy and its apologists will often be on hand to explain that the latest outrage was forced upon Tehran or is a response to some legitimate grievance, the lawlessness of the Islamic Republic is in its DNA, beginning with the takeover of the American Embassy in the year of its foundation, 1979. Since then there has been the so-called Tanker War of the 1980s, Iran’s first experiment with state piracy to disrupt world oil markets, the use of Iran’s own Embassies to wage a campaign of terrorism and assassination from Buenos Aires to Berlin in the 1990s, the murder of hundreds of British and American troops in Iraq in the 2000s, and underwriting the Assad regime’s genocidal violence in Syria since 2011. On and on it goes. Smaller incidents like the abduction of a Royal Naval ship in 2007 often get lost in this rap sheet. But it all adds up to a simple fact: no matter the diplomatic mood, the Islamic Republic can be found to have attacked Westerners and Western interests.

There is much to criticise in how President Trump has gone about his Iran policy. The withdrawal from the JCPOA without securing the agreement of the EU and UK, thereby creating a split within the Western coalition as his first step, was a terrible mistake, not least because the nuclear file is secondary to Iran’s imperial adventures, and Trump’s actions have diverted all the diplomatic energy into technical squabbles over JCPOA or some new nuclear deal, rather than rallying allies to push back on Iran where it matters, on the ground in the region. Nonetheless, the threat from Iran is real, and whatever British policy on the JCPOA is going to be, the UK now firmly needs a robust new Gulf strategy to ensure its national interests are secured.

Despite the UK trying to keep the JCPOA alive, which might have been expected to win some gratitude from Iran, a diplomatic breakthrough looks further and further away. A return to a prior status-quo based around limited Iranian containment looks less and less feasible as Iran gains confidence. As worrying as escalation is, the precedent of unpunished state piracy is at least as dangerous In certain situations, once extensive diplomatic efforts have been exhausted, force must be matched by equal or greater force in order to break an actor’s will to sustain a negative relationship, one that threatens not only the UK’s national interests, but British lives. At present, Tehran shows little inclination for de-escalation, much less repentance for recent hostile transgressions, and the range of options available to alter that calculation are limited.

In the meanwhile, there are a series of measures that can be taken to counter this now-established threat to Western interests in the Gulf region. Principally, the UK now requires an urgent rethink into its strategic relations with not only Gulf states, but also fellow Western partners which rely upon the region for the maintenance of their domestic energy imports. To this end, the UK should consider increasing its current defence footprint in the region, known as Operation Kipion. Part of 30 nations working in cooperation, and based in Bahrain, it includes four Royal Navy minesweeping vessels which patrol the Gulf – crucial considering the recent incidents involving Iranian sabotage on multiple oil tankers.

Whilst increasing Operation Kipion would not merit a ‘return to the Gulf’ moniker – not least because the UK has never left the region – it will require a more consistent presence than has been thought necessary up to this point in relation to the range of threats to the UK’s national interests. Particularly, the success of the IRQCN in being able to intercept, board, seize and transport back to Iranian waters Western oil tankers serves notice that despite the hard work of HMS Montrose, the Type 23 Frigate currently conducting maritime escort services in the Gulf, numbers truly make a difference. Unable to assist the Stena Impero due to the sheer size of the region, the addition of the HMS Duncan and HMS Kent cannot come quickly enough.

The UK and the US have stated that they are not seeking conflict with Iran, and Trump’s refusal to give the go-ahead when presented with contingencies for kinetic action in retaliation to downing a drone in late June testifies to how unwilling he is to act in this way. Yet this evident fear of military action from the West creates a problem in establishing the deterrence that would be needed to prevent conflict. Still, there are signs of progress. The announcement by Washington last month of a potential US-managed maritime Task Force, led by a regional ally, intended to deter aggressive state behaviour in the crucial sea lanes in the Gulf region, is absolutely something which the Royal Navy should seek to support alongside both European allies and regional partners alike. Europe is still heavily reliant on Arab oil, and the UK imports over 39 million barrels annually, too. There is a common British, European, and Arab interest in ensuring having Iran desist from its destabilising activities.

Tied to a refined strategic outlook for the Gulf region, UK defence, and in particular the Royal Navy, requires additional funding to ensure that the UK’s national interests are protected in an ever increasingly unpredictable region. UK Foreign Secretary Jeremey Hunt has advocated for defence spending to rise from to 2% of GDP to a modest 2.5% over the next five years, increasing the MoD’s budget by approximately £15 billion (2019 rates). This would allow for not only the budgetary deficit in UK defence to be dealt with, but also allow further spending in both personnel and equipment, two areas in dire need of investment.

As the incoming Prime Minister, Boris Johnson will have many issues to resolve, not least leaving the European Union in a timely fashion and attempting to bridge the national divide created over the past three years. However, national defence is the foremost responsibility of any Prime Minister. Iran shows no sign of de-escalation, despite what is sure to be intense diplomatic activity over the coming days regarding the seizure of the Stena Impero. Even after this is resolved, if it is resolved, Iran remains a menace to the security of the wider Gulf region, and in particular to any nation vested in the vulnerable Strait of Hormuz.

Robert Clark ( @RobertClark87 ) is a postgraduate Defence researcher at King’s College London, and previously served in the British Army. Kyle Orton ( @KyleWOrton ) is an independent researcher focused on the Middle East.