Thousands of outraged Armenians, mostly young, invaded Republic Square on April 13. The protests gradually spread to other major cities of the small nation of the South Caucasus, including Gyumri and Vanadzor.
The pressure on Mr. Sargsyan, 63, resigned remarkably on Monday after soldiers from a company of the country's prestigious peacekeeping force, which had served abroad in Iraq, Afghanistan and Kosovo, joined forces the march in Yerevan with their uniforms.
"All the momentum was with the street," said Thomas de Waal, an expert on the Caucasus region at Carnegie Europe in Brussels.
Tuesday is Armenia's Genocide Commemoration Day, when many of the more than 2.6 million people in the country take to the streets. It was hoped that it would quickly become a major demonstration against Sargsysan that would have been unthinkable to suppress by force, said Aleksandr M. Iskandaryan, director of the Caucasus Institute in Yerevan.
Mr. Sargsyan had promised last year not to try to extend his term in office by becoming prime minister when his presidential term ended.
Karen Karapetyan, who had just left the post of prime minister to make way for Mr. Sargsyan, intervened as Acting Prime Minister.
Rapid events disordered the country. The new Constitution invests considerable power in Parliament, and some early elections are expected.
The demonstrations were fueled by a new generation of disenchanted Armenians with the small elite of politicians and their oligarchic allies who long controlled the government and much of the economy, analysts said. The protesters dismissed the standard argument that Armenia needed an invariable leadership to negotiate an end to the conflict with neighboring Azerbaijan and deal with tense relations with Turkey on the other side.
"There is a new generation that wants change," Mr. de Waal said. "The problem is that they do not really have a leader."
Nikol Pashinyan, a member of the opposition Parliament that led the protests, lacks a party and a large electorate.
Mr. Sargsysn agreed to meet Mr. Pashinyan on Sunday, but left the meeting in a matter of minutes, claiming he was being blackmailed. Then, Mr. Pashinyan and two of his opposition allies were arrested during the night, after dozens of protesters were also arrested. The three leading figures of the opposition were released on Monday.
Mr. de Waal compared the protesters with the professional and urban elite that came to protest against the re-election of President Vladimir V. Putin in 2012 after being prime minister for a period to avoid the limits of the mandate. Some Armenians even referred to their leader's maneuver as "throwing a Putin," said Mr. Giragosian of the Center for Regional Studies.
Unlike the Armenian leaders, however, Putin repressed strongly, sending riot police and making an example of some protesters with long prison sentences. Any sign of government change through protests, like the one in Ukraine, shakes the Kremlin, so the protests in Armenia gained little attention on Russian state television until Mr. Sargsyan resigned.
Maria Zakharova, spokesperson for the Russian Ministry of Foreign Affairs, praised the transition for being peaceful, saying: "Armenia, Russia is always with you!"
Armenia, a Soviet state until it declared independence in 1991, remains a close partner of Russia in a volatile region, with a Russian military base in Gyumri, has been blocked for two decades in a low-grade war with Azerbaijan, another former Soviet republic, for control of a disputed enclave called Nagorno-Karabakh Some Armenians accuse Russia of fueling a new outbreak of the struggle in 2016 by selling arms to both sides.
Azerbaijan has long exploited riots in Armenia to try to make a profit in the conflict, which may be one of the reasons why Mr. Sargsyan acted quickly, analysts said, Beyond that, the beginning of his presidency in 2008 was marred by street protests in which 10 people died and 100 were injured, so he was determined to keep the peace this time, they said.
In addition to the political and territorial tensions, the country has also suffered a rocky economy in recent years. Armenia relies heavily on remittances from its diaspora, which grows some 50,000 people a year, said Andrei G. Areshev, a researcher from the Caucasus at the Russian Academy of Sciences in Moscow.
Armenians working in construction and other manual jobs in Russia were hard hit by the devaluation in the ruble in 2015, but they sent home $ 1.07 billion last year, according to Central Bank records. As prime minister, Mr. Karapetyan helped the economy grow by fostering a technology sector, among other steps.
Given that most key government officials, including the interim prime minister, are allies of Sargsyan, it is not clear that his resignation will bring any immediate change, or what the protesters can do next.
"The government expected the tide to subside, but the opposite happened," Iskandaryan said in Yerevan.
Continue reading the main story