But the announcement of this latest sentence is likely intended more as a symbolic gesture than as meaningful enforcement of the law. It comes about a week after it was announced that the judiciary had also upheld 10-year prison sentences that had been given to three different American citizens and a permanent resident of the United States. Each of those individuals was subject to seemingly unsubstantiated accusations of spying.

One, the Princeton graduate student Xiyue Wang, was arrested on the basis of the large number of photocopies he had made as part of his historical research. Another, the Lebanese information technology expert Nizar Zakka, was detained after being invited by the government to give a conference on women in the IT field at an industry conference.

The denial of appeals for these individuals and for father and son Baquer and Siamak Namazi may be seen as a gesture of defiance against the United States, coming as it does at a time of increased tensions between the two countries over the future of the Iran nuclear deal and other, related issues. Last month, US President Donald Trump signed legislation expanding sanctions on the Islamic Republic over its ballistic missile program and its support of international terrorism. Tehran quickly fired back by passing its own legislation expanding both of these activities, as well as by threatening to resume nuclear activities at a higher level than before.

These gestures have also been bolstered by general anti-American rhetoric, which is presumably driving both the domestic arrest and prosecution of US-linked individuals and the provocation of American and US-allied forces in the Persian Gulf region. Last week, around the same time as the judiciary announced the confirmation of the dual nationals’ sentences, the head of Iran’s air defense forces declared that the Islamic Republic had warned off two American spy plans in a six month period.

This claim was conveyed through an Arabic news source and thus presumably doubled as a threat to Saudi Arabia and other US-backed allies. In the interview, Brigadier General Farzad Esmaili said that the Iranian military “will not hesitate to destroy” an American craft that violates Iranian airspace.

Such statements are rather common among Iranian military leaders and especially among officers in the Islamic Revolutionary Guard Corps, but they are highly dubious. Although the Iranians routinely announce the unveiling of new military technology, independent experts often disregard this as non-working mock-ups or as old technology with superficial changes made to its external appearance. In raw terms, the Iranian air force is larger than those of its Arab neighbors but it is also badly outmoded, with most of the craft dating back to the mid-twentieth century.

Iran also lacks large warships capable of engaging American destroyers or aircraft carriers, but this has not stopped the IRGC and the military from boasting of readiness of war. Early this year, the country premiered a propaganda film that depicted a figured modeled after IRGC Quds Force commander Qassem Suleimani leading a small Iranian naval force to victory over a much larger American one. In previous years, the country has held military exercises to demonstrate the “swarm tactics” that it would supposedly employ to destroy large American naval vessels with large numbers of small attack boats and aircraft.

Accordingly, the IRGC has used these sorts of small boats to antagonize US Navy vessels in the Persian Gulf. Instances of close encounters on the water involving Iran and the US more than doubled in the year following the Iran nuclear deal. Reports of such incidents continue to emerge, with very difference descriptions coming from the Iranian and American side.

This was the case on Sunday, when Iran’s English-language propaganda broadcaster Press TV claimed that the Iranian Navy had “warned off and American warship” while rescuing a small Iranian boat that was stranded in the Gulf of Oman. But as reported by the Associated Press, the US Navy’s version of events does not have its warship coming any closer than 75 nautical miles from the stranded dhow. Instead, another vessel approached the scene and remained in radio contact with the Iranians to offer assistance, before being rebuffed.