- In recent months, ISIS stepped up its efforts to target Iran
- Iran is targeted for cash, guns it poured into battle against ISIS
- ISIS threatened to "cut the necks" of Iran's Shias in new video
The assault in June, stunning in both its symbolism and execution, left 18 people dead and caught Iranian security forces off-guard. It was the first Islamic State attack in Iran, whose Shiite Muslim majority the militants regard as apostates.
In recent months, the Islamic State has stepped up its efforts to target Iran, releasing a stream of propaganda, vowing more bloodshed and boosting recruitment among Iran's minority Sunnis, some of whom carried out the June attack.
Iran is a target for the cash, guns and troops it has poured into the battle against the jihadists, whose lightning ascent in Iraq and Syria three years ago threatened Iran's security. Last week, Iranian authorities arrested more than two dozen people they said planned to bomb religious sites with smuggled explosives. The Islamic State then threatened to "cut the necks" of Iran's Shiites in a new video featuring a Farsi-speaking militant.
The escalation could inflame a region already beset by conflict, and stoke domestic instability in Iran. There, marginalized Sunnis have grown increasingly receptive to the Islamic State's appeal. Situated along Iran's porous borders, the communities, which make up about 10 percent of Iran's population of 80 million, may make fertile ground for a jihadist group working to replenish its ranks.
"Iran is fighting the Islamic State on multiple fronts, and Iraq and Syria is certainly one of them," said Dina Esfandiary, a MacArthur fellow at the Center for Science and Security Studies at King's College London. "But the fight against the Islamic State inside Iran has become even more important."
Suffering decades of neglect, Iran's Sunni communities are "a good target for the Islamic State," said Esfandiary, who co-wrote a paper on Iran's policies toward the militants. "It's a population ripe for recruitment," she said.
Indeed, Iran's Sunni populations hail mainly from two ethnic minorities, including the Kurds who live along the Iraq border in the west, and the Baloch community in the southeast near Pakistan. In both places, poverty, repression and black market economies have allowed Sunni radicalism to creep in and take root.
Baloch areas in particular are "severely underdeveloped," according to the State Department's 2016 human rights report on Iran, and unemployment hovers at about 40 percent. In Kurdish communities, residents complain of widespread discrimination and arbitrary arrests. Rights groups have slammed Iran for the detention and execution of dozens of Sunni Kurds, often for unspecified crimes.
It is unclear how many Iranians have joined the Islamic State, but estimates from Kurdish media and analysts vary from dozens to hundreds. In the group's first Persian-language video, released in March, at least one of the militants identified as Baloch.
According to a report from the International Center for Counter-Terrorism at The Hague, seven Iranians carried out suicide operations for the Islamic State from November 2015 to December 2016.
"The Iranians do have to worry about it. The numbers aren't insignificant," said Alex Vatanka, senior fellow and Iran expert at the Middle East Institute in Washington. Even if only a few end up radicalized, he said, "once they have the support of the ISIS machinery to carry out attacks, they can do real harm, as we've seen with the attack in June."
At least four of the five assailants came from the same Kurdish town in western Iran, about 10 miles from the Iraq border, officials said. The attackers had all belonged to local Islamist militant groups before traveling abroad to fight for the Islamic State.
For years, local and other militants used the area as a logistics hub to attack U.S. forces across the border in Iraq. But the Kurdish militants' most recent return to Iran, after they had traveled to Iraq and Syria, exposed weaknesses in the country's counterterrorism strategy, analysts said, which emphasized operations abroad but may have downplayed the potential for radicalization at home.
Iran's lenience "meant that there were effectively ready-made smuggling routes that Iranian Kurds could exploit to help avoid detection" in the event of an attack, Guillou said.
In Baloch areas, which border some of the most lawless territory in Pakistan and Afghanistan, local insurgents have also adopted a jihadist message to mobilize against the government in Tehran.
They were once leftist nationalists, but over the past decade or so, they "have now begun to take up the mantle of jihad, and a sectarian Sunni message," Vatanka said. "This is very dangerous from Iran's internal security point of view."
The groups are believed to have cross-border links with like-minded militants in Afghanistan and Pakistan. But, analysts say, they have not yet pledged allegiance to the Islamic State.
Still, as the Islamic State loses territory in Iraq and Syria, it may seek to coax local groups into providing its fighters sanctuary or establishing a new base.
Among the Baloch militants, "there are certainly those that would be receptive to involvement in transnational jihad," Guillou said. But "the real risk concerns how the state deals with this increased threat from the Sunnis."
"So far, the security forces have really focused very tightly on suspected militants," he said, adding that a broader crackdown could push some of Iran's more conservative Sunnis "into the jihadi camp."
The government under President Hassan Rouhani has also reached out to Sunni leaders, in a bid to immunize the state against the growing threat. Rouhani won reelection with landslide majorities in both Kurdish and Baloch areas in May. But his efforts so far, analysts say, have been halting and ultimately failed to impress.
"There are many officials within the administration that realize how important it is to reach out to Sunni communities, to talk to them," Esfandiary said.
But it hasn't gone very well, she said, "not least because it was sort of a halfhearted attempt" on the part of the government.
"There are still discrepancies between the way the minority communities are treated compared to normal Shia Iranians," she said. "It's a big problem for the Iranian government."
(This story has not been edited by NDTV staff and is auto-generated from a syndicated feed.)