The 36th anniversary of the U.S. Embassy takeover in Tehran unfolded Wednesday with the familiar protests and chants of “Death to America.” But there was also a new twist: growing battles between hard-liners and their opponents over how much Iran will change after a landmark nuclear deal with the United States and other powers.

And in the middle was Iran’s ultimate power, Ayatollah Ali Khamenei, who is trying to fine-tune his message that the nuclear accord can stand but that future openings to Washington are not an option.

The demonstration Wednesday in front of the brick walls at the former U.S. diplomatic compound — scene of a 444-day hostage standoff — was just the latest show of resolve by Iranian conservatives in a running showdown with reformers that goes back decades.

But this anniversary was infused with a sense of greater urgency for both sides. A wave of recent arrests — whose targets included Iranian journalists and a Lebanese technology activist who worked in the United States — could deepen Iran’s political confrontations even as the first steps of the nuclear deal take shape.

President Hassan Rouhani seeks to leverage the nuclear pact into wider outreach to the West. The goals include greater business investment and a stronger voice in regional affairs, such as the battles against the Islamic State and the fate of Syrian President Bashar al-Assad, an Iranian ally.

At the same time, powerful detractors — including the hugely influential Revolutionary Guard Corps — worry that Rouhani is pressing too hard and too fast. Any rapid moves, in their view, could undercut their voice in Iranian policymaking.

The supreme leader, Khamenei, may now be offering calculated nods in each direction.

“Khamenei has to play a delicate game,” said Mehrzad Boroujerdi, a professor who follows Iranian affairs at Syracuse University. “If he sends conflicting messages, so be it. . . . It reflects just how conflicted things have become in Iran since the nuclear deal.”

In a crucial move to end internal debate, Khamenei last month endorsed the nuclear accord that limits Iran’s nuclear program in exchange for a reduction in international sanctions.

But Khamenei cannot afford to alienate groups that consider themselves the guardians of the Islamic system. Khamenei has repeatedly offered them rhetorical assurances — denouncing any attempts at U.S. “infiltration” and portraying Washington as Iran’s unrivaled enemy.

Earlier this week, Khamenei told a group of students that the phrase “Death to America” still rang with “strong support” among Iranians, although a Twitter message from his account on Tuesday explained that it was not aimed at the United States as a nation. Instead, he wrote, the phrase is a critique of U.S. policies and “arrogance.”

Another apparent fissure emerged Tuesday when Iranian state TV announced the arrest of a Lebanese technology expert, Nizar Ahmad Zakka, who worked in the United States and was accused by Iran of “deep ties” to the U.S. military. Zakka was in Tehran in September to attend a conference at the invitation of Rouhani’s government when he was reportedly detained. Zakka’s family denies he has links to the U.S. military.

Rouhani’s government has not directly commented on the reported arrest. But the detention could be interpreted as another warning shot by hard-liners seeking to undermine his bids at outreach.

Iran’s judiciary — believed directed by Iran’s ruling clerics — also has ordered the detention of at least four Americans, including Washington Post journalist Jason Rezaian .

Rouhani fired back Wednesday with sharp criticism of the recent arrests of Iranian journalists and online activists.

“We should not arrest people without reason, making up cases against them and [saying] they are a part of an infiltration network,” Rouhani told a cabinet meeting, according to Iranian news reports.

A state prosecutor, Ebrahim Raeisi, told the rally outside the former U.S. Embassy that the journalists and others were part of a “network of penetration” that he claimed held ties to the United States.

“Under no circumstances will we allow penetration of Americans in economic, social and cultural areas,” he told the crowd.

Nisrene Yousif, a Beirut-based political analyst and researcher, attributed the sharpening tensions to “internal political competition” before parliamentary elections in February.

But there is also a streak of Iranian pride that touches each level of its affairs, a belief that the country stands as an ideological and technological leader for the Islamic world. In this view, any rapprochement with the United States is seen as a potential loss for Iran.

Conservatives “have a traditional ideology, which resents the U.S. and believes that
Iran has sacrificed and should not give concessions,” Yousif said.

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