Striking at the heart of the Iranian establishment, ISIS brings its sectarian violence to Tehran.

At least twelve people were killed and more than 30 wounded on Wednesday in twin attacks on the mausoleum of Ayatollah Ruhollah Khomeini, the founder of the Islamic Republic of Iran, and the parliament building in Tehran. According to Iran's Tasnim news agency, the parliament attackers took hostages, including MPs. ISIS quickly claimed the suicide and gun attacks via its affiliated Amaq news agency, its eighth claim since the start of the Muslim holy month of Ramadan.

Iranian state media reported that four perpetrators had been killed following the attack. There were also reports that one of the perpetrators was a woman. Parliament Speaker Ali Larijani dismissed the attack as a "minor issue" and said that the "coward terrorists" that entered the building were robustly confronted. Meanwhile, Iranian officials said a third attack had been foiled by security forces.

The attacks in Tehran are significant and they are in line with the ideology espoused by ISIS. In ISIS' eyes, both the shrine and parliament are manifestations of disbelief and innovation. Salafi-jihadis like ISIS deem the erecting of shrines and the visiting of them to contradict their narrow, puritanical interpretation of the unity of God. Similarly, the parliament building is home to Iran's, albeit theocratic, democracy. As far as ISIS is concerned, this is a manmade innovation that stands in opposition to the sovereignty of God.

ISIS' claim of responsibility came quickly. The group said its fighters were involved in both attacks. While a number of other attacks claimed by ISIS in recent weeks have been described as tenuous due to lack of evidence substantiating the group's involvement, in this attack an official ISIS outlet has reportedly released video footage from inside the Parliament building.

This is ISIS' first attack in Iran. In March this year, the group released a propaganda video in Farsi, threatening to conquer Iran and return the Persian nation to being Sunni Muslim, as it was once before. The video was released by ISIS' Diyala Province, which stretches from Baghdad in Iraq towards the border with Iran to the east. ISIS has also published four editions of Rumiyah, the group's online propaganda magazine, in Farsi, while translations of essays into the language and subtitled videos have been circulated by the group since 2015.

Iran is a Shia majority country, with around 90-95 per cent of the population following the tradition. The Persian nation also accounts for 37-40 per cent of the global Shia population. As a Shia majority country in the Middle East, Iran is certainly in the minority, and this is further compounded by it being a Persian country in a neighbourhood of Arab nations. Countries neighbouring Iran such as Iraq and Pakistan, which account for 11-12 per cent and 10-15 per cent respectively of the global Shia population, have suffered from sectarian-driven terrorism at the hands of ISIS.

Iran has been the subject of hostility from ISIS in particular given the role Tehran has played in fighting the group in Iraq and Syria, where Tehran has been propping up the Assad regime. Through the deployment of its own military personnel, including the Iranian Revolutionary Guards Corps, and the supporting of proxies, Shia militias, and terrorist groups such as Hizbullah, Asaib Ahl al-Haq, and Harakat al-Nujaba, Tehran has been heavily involved in military operations to dislodge the group from territorial strongholds in Iraq and Syria.

The attack comes just weeks after the counter-terrorism summit in Riyadh, in which leaders from both Saudi Arabia, Iran's regional rival, and the US, Tehran's longstanding foe, described Iran as the largest state backer of terrorist activity and the spearhead of global terrorism. Similarly, it has only been a couple of weeks since the re-election of President Hassan Rouhani, and while the economy and regional relations were important challenges for him to navigate, the ISIS attack in Tehran will means the president now has serious domestic security threats to overcome, too.