That operation is widely understood to have been carried out in retaliation for British Royal Marines’ seizure of a tanker carrying Iranian oil toward Syria on July 4. The earlier incident was explained as an instance of enforcement of European Union sanctions on trade with entities affiliated with the regime of Bashar al-Assad, who is credibly accused of multiple, serious human rights violations. But Tehran has rejected the British explanation and labeled the seizure of the Panamanian-flagged Grace 1 as a violation of international law while also claiming that the subsequent seizure of the Stena Impero was justified by the ship turning off its signal for too long and entering the Strait of Hormuz via the wrong lane. The ship’s operator has stated that the crew adhered to all relevant regulations during its attempted transit of the Strait.

IRGC officers and other hardline persons in the Islamic Republic have also undermined their own government’s cover story with statements praising the seizure of the Impero, floating the idea of exchanging one ship for the other, and promising further retaliatory measures in response to Western pressure or international efforts at safeguarding the vitally important waterway that passes between Iran and Oman. In fact, statements undermining the official explanation emerged even before the official explanation itself, when some hardliners responded to the Grace 1 seizure by immediately advocating for the capture of a British ship.

The IRGC even attempted to follow up on this threat just days after the Grace 1 incident, which took place near the British overseas territory of Gibraltar, at the mouth of the Mediterranean. As a British-flagged ship called the Heritage was transiting the Strait of Hormuz on July 11, it was reportedly approached by at least three IRGC gunboats, which attempted to encircle it in a manner similar to what such boats would do just over a week later with the Impero. However, the Heritage was closely shadowed by a Royal Navy frigate, the HMS Montrose, which was able to insert itself between the commercial ship and the IRGC, warning off the latter without further incident.

The latest information concerning the subsequent encounter between the IRGC and the Impero suggests that a similar Royal Navy response failed. Iranian state media released video on Monday purporting to show another British warship, Foxtrot 236, in the vicinity of the British-flagged commercial ship at the time of its seizure. Accompanying audio features an IRGC officer communicating with the Foxtrot by radio. “You are ordered to not interfere in my operation,” he says. “You are required not to interfere in this issue.”

Following a response from the British warship, the officer underscores his order with a threat: “Don’t put your life in danger.” Such statements are typical of the behavior of the IRGC, which has on numerous occasions ordered its fast-attack gunboats to approach US warships in a threatening manner as they transit the Strait. In some cases, those boats have only withdrawn after warning shots were fired. Yet Iranian state television has depicted some such incidents as the Islamic Republic successfully standing up to Western impositions.

This was no doubt the purpose of Monday’s video, which was released at roughly the same time as another British warship, the HMS Duncan, arrived in the region to accompany the Montrose and assist in providing security to British-flagged vessels as they transit the Strait. Last week marked the first instance of such a passage, and the commercial ship in question was shadowed at a moderate distance by the Montrose. At the same time that the United Kingdom has committed to more such escorts, it has also called for a European-led security force to help guarantee the safety of commercial shipping in the face of Iranian threats.

For its part, Tehran has denounced all such plans as “hostile” and “provocative,” with President Hassan Rouhani saying, “The presence of foreign forces will not help the region’s security and will be the main source of tensions.”

This remarks came in the wake of a meeting with the Omani State Minister for Foreign Affairs, Yusuf bin Alawi, whose visit yielded affirmation of the shared responsibility of the two nations to lead the way in providing security to the Strait. But while Oman apparently shares this attitude, its traditional role as a neutral party in regional conflicts precluded Alawi from rejecting Western security measures outright. The Omani minister denied that his visit was intended as mediation for the current conflict, although the Arabian nation has evidently played that role before, as by facilitating the negotiations that would eventually lead to the 2015 Iran nuclear deal.

That agreement, formally known as the Joint Comprehensive Plan of Action, remained a point of international focus on Monday, after diplomats from Iran and the five other remaining signatories of the agreement met in Vienna the previous day. US President Donald Trump withdrew from the agreement in May 2018 after two years of condemning it as one of the worst deals ever negotiated. In recent weeks, Iran began violating its provisions as well, first by exceeding limits on the amount of nuclear material it has stockpiled and then by enriching uranium past the level of fissile purity specified in the agreement.

The extent of Iran’s violations remains unclear, but its representatives in Vienna continued to insist that all violations are reversible in the event that Britain, Germany, and France undertake measures to protect Iranian exports against the effects of US sanctions. In previous discussions, the Iranians suggested that their demands could be met simply through the operationalization of Instex, a special payment mechanism jointly created by the three European signatories to supposedly make possible transactions that circumvent the US financial system. But on Sunday, Iran’s Deputy Foreign Minister Abbas Araqchi appeared to broaden the minimum criteria for an Iranian return to compliance, by connecting the nuclear deal to the tanker disputes.

Although the UK has justified the seizure of the Grace 1 in terms of lawful sanctions on the Assad regime, which are unrelated to either the Iranian nuclear program or Iranian oil exports in general, Araqchi characterized them as an impediment to those exports and thus as a violation of the JCPOA. The consequence of this argument would seem to be that the Iranian regime considers itself justified in demanding additional European concessions on any number of issues, as long as they can be connected in some way to Iran’s oil industry. And this is in keeping with statements made by Tehran in the wake of the JCPOA’s implementation, when they noted that they would consider any increase in sanctions to be a violation of the deal, even if those sanctions stemmed from unrelated matters such as the regime’s human rights violations or support of terrorism.

Even after imposing on the Vienna dialogue a demand for resolution of the tanker crisis, Araqchi struck and optimistic tone about the outcome of that discussion, stating publicly that all parties had expressed ongoing commitment to the JCPOA. The deputy foreign minister did, however, acknowledge that the core issues remained unresolved, and a Chinese representative to the talks told the press that there had been “tense moments” in the proceedings. Separately, it was reported that Iran’s atomic energy authority had reiterated threats to extend its violations of the agreement, specifically citing plans to resume operations at the Arak heavy water plant, which is capable of creating plutonium that might be used for a nuclear weapon.

While it may be true that Britain remains committed to upholding the nuclear deal, it is clear that the government has no interest in capitulating on the tanker crisis for that sake. It was reported on Monday that Foreign Secretary Dominic Raab had explicitly rejected the notion of swapping the Grace 1 for the Stena Impero. Meanwhile, an editorial by Atlantic Council President Frederick Kempe suggested that the existence of this tacit offer by the Islamic Republic constituted one of several “surprising signs” that the US strategy of “maximum pressure” was pushing Tehran in the direction of renewed negotiations.

That CNBC editorial went on to suggesting laying aside “all the transatlantic and domestic differences that have poisoned the Iran debate” in order to determine how best to expand upon that strategy without risking conflict. That, of course, is the stated goal of separate plans being promoted by the US and the UK regarding collective deterrence efforts in and around the Persian Gulf. France, Italy, and Denmark have all express tentative support for the British plan, although France specified that it would only commit to sharing operational intelligence and strategy, not to deploying additional military assets to the region.

However, this may not be sufficient deterrence, given Iran’s current posture. And the UK may not be able to make up the shortfall on its own. This was the conclusion of a Business Insider article which analyzed both American and British naval capacities on Monday. It explained that both capacities had declined significantly in recent years even as the technological superiority of their militaries over those of would-be adversaries like Iran have grown.

This situation hardly make it likely that Iran would be able to live up to its own claims about being able to triumph in a direct conflict. But it may offer a sort of invitation to more provocative behavior for the IRGC, which has previously promoted “swarm tactics” as a supposed means of taking down technologically superior vessels with large numbers of small, fast moving craft. Furthermore, there is good reason to worry that the Revolutionary Guards will act upon this invitation, especially following the release of video from the incident in which a lone British warship failed to insert itself between small IRGC boats and the British-flagged vessel they had resolved to capture.