Iran on Saturday said it detained an Iranian-American leader of a little-known California-based militant opposition group for allegedly planning a 2008 attack on a mosque that killed 14 people and wounded over 200 others.

Iran’s Intelligence Ministry also alleged Jamshid Sharmahd of the Kingdom Assembly of Iran planned other attacks around the Islamic Republic amid heightened tensions between Tehran and the U.S. over its collapsing 2015 nuclear deal with world powers.

It was unclear how the 65-year-old Sharmahd, whom Iran accused of running the opposition group’s Tondar militant wing, ended up detained by intelligence officials. The Intelligence Ministry called it a “complex operation,” without elaborating. It published a purported picture of Sharmahd, blindfolded, on its website.

Iranian Intelligence Minister Mahmoud Alavi later appeared on state TV himself in the studio, saying Sharmahd had been arrested in Iran, without elaborating.

Requests for comment sent by email to the Glendora-based Kingdom Assembly of Iran were not immediately answered and a telephone number for the group no longer worked.

The U.S. State Department, which mentioned how Sharmahd earlier had been targeted for assassination in a recent report called “Outlaw Regime: A Chronicle of Iran’s Destructive Activities,” did not immediately respond to a request for comment.

Iranian state television broadcast a report on Sharmahd’s arrest, linking him to the 2008 bombing of the Hosseynieh Seyed al-Shohada Mosque in Shiraz. It also said his group was behind a 2010 bombing at Ayatollah Ruhollah Khomeini’s mausoleum in Tehran that wounded several people.

The report also alleged without providing evidence that Tondar, or “Thunder” in Farsi, plotted attacks on a dam and planned to use cyanide bombs at Tehran’s annual book fair.

State TV later aired footage of Sharmahd interspersed with footage from the moment of the 2008 explosion at the Shiraz mosque. Sharmahd’s face appeared swollen and the style of the footage resembled one of what a rights group has identified as over 350 coerced confessions aired by the broadcaster over the last decade.

The Intelligence Ministry has not said what charges Sharmahd will face. Prisoners earlier accused in the same attack were sentenced to death and executed.

The Kingdom Assembly of Iran, known in Farsi as Anjoman-e Padeshahi-e Iran, and Tondar seek to restore Iran’s monarchy, which ended when the fatally ill Shah Mohammad Reza Pahlavi fled the country in 1979 just before its Islamic Revolution. The group’s founder disappeared in the mid-2000s.

Iranian intelligence operatives in the past have used family members and other tricks to lure targets back to Iran or friendly countries to be captured. An alleged Iranian government operative who allegedly tried to hire a hit man to kill Sharmahd disappeared in 2010 before facing trial in California, likely having returned to Iran.

A 2010 U.S. diplomatic cable from London later published by WikiLeaks shows that a Voice of America commentator said that same operative earlier had been in contact with him. British anti-terror police later warned the commentator that he “had been targeted by the Iranian regime,” the cable said.

The two cases marked “a clear escalation in the regime’s attempts to intimidate critics outside its borders, and could have a chilling effect on journalists, academics and others in the West who until recently felt little physical threat from the regime,” the cable said.

Sharmahd last appeared in an online livestream video on Dec. 29, according to his group’s website, speaking in Farsi while sitting in a black chair in front of a black background.

“We are not only seeking the liberation of the homeland, but we are also moving towards a special direction, and that is to be Iranian,” Sharmahd said at one point in the video. “Because we have heard that once upon a time some people were living in the region who were able to build an empire.”

While overshadowed by other exiled opposition groups, Iran reportedly brought up the Kingdom Assembly multiple times while negotiating the terms of the 2015 deal, which saw Tehran limit its enrichment of uranium in exchange for the lifting of economic sanctions.

Iran’s Foreign Ministry spokesman Abbas Mousavi reacted to the news by criticizing the U.S. for allowing Sharmahd and others to live in America.

The U.S. “must be responsible for supporting terrorist groups which are inside of this country and carry out and lead terrorist acts against the Iranian people,” state TV quoted Mousavi as saying.

A statement attributed to Tondar claimed the assassination of an Iranian nuclear scientist in 2010 by a remote-control bomb, though it later said it wasn’t responsible. Suspicion long has fallen on Israel for a string of assassinations targeting scientists amid concerns about Iran’s nuclear program, which the West fears could be used to develop a nuclear bomb. Iran long has maintained its program is for peaceful purposes.

Sharmahd’s reported arrest comes as tensions remain inflamed by President Donald Trump’s 2018 decision to unilaterally withdraw America from the nuclear deal. A series of incidents last year were capped by a U.S. drone strike in January killing a top Iranian general in Baghdad. Iran responded by launching a ballistic missile attack on U.S. soldiers in Iraq that injured dozens.