FEATURE | Options for Trump in Iran: maritime pressure, targeted military strikes

“For this sort of thing to succeed, you have to have crowds in the streets for a much longer period of time. And you have to have a breakup of the state. Some segments of the state, and particularly the security forces, have to defect," he said. Iran's Foreign Ministry declined to comment.

Supreme Leader Ayatollah Ali Khamenei, 86, has survived several past waves of unrest. This is the fifth major uprising since 2009, evidence of resilience and cohesion even as the government confronts a deep, unresolved internal crisis, said Paul Salem of the Middle East Institute.

For that to change, protesters would have to generate enough momentum to overcome the state’s entrenched advantages: powerful institutions, a sizeable constituency loyal to the clerical rule, and the geographic and demographic scale of a country of 90 million people, said Alan Eyre, a former US diplomat and Iran expert.

Survival, however, does not equal stability, the analysts said. The Islamic Republic is facing one of its gravest challenges since 1979. Sanctions have strangled the economy with no clear path to recovery. Strategically, it is under pressure from Israel and the United States, its nuclear program degraded, its regional “Axis of Resistance” proxy armed groups weakened by crippling losses to allies in Lebanon, Syria and Gaza.

Nasr said that while he didn't think the Islamic Republic had reached the “moment of fall", it was, "now in a situation of great difficulty going forward." The protests began on December 28 in response to soaring prices, before turning squarely against clerical rule. Politically, the violent crackdown has further eroded what remained of the Islamic Republic's legitimacy.

US-based rights group HRANA says it has verified the deaths of 573 people, 503 protesters and 69 security personnel. More than 10,000 have been arrested, the group said.

Iran has released no official toll, and Reuters was unable to independently verify the figures.