Kazakhstan President Nursultan Nazarbayev, who ruled the country for 30 years, resigned in an an unannounced television address on Tuesday. "I have decided to give up my powers as president," the 78-year-old said, without providing an explanation for his decision.

In accordance with the constitution, the speaker of the upper house of parliament, Kassym-Jomart Tokayev, will serve as the country's interim president. It is not yet clear when fresh elections will be held.

Nazarbayev's resignation is only the second time the president of a former Soviet republic has stepped down voluntarily. Russian President Boris Yeltsin was the first to do so in 1999, but he also named a successor, Vladimir Putin.

Nevertheless, Nazarbayev's resignation should not come as a surprise, according to Sebastian Schiek of the Berlin-based German Institute for International and Security Affairs. "There were rumors" it could happen, he said, noting that laws passed in recent years indicated a leadership change was imminent.

One of these laws, said Schiek, stipulates that a former president remains in charge of the country's security council and thus controls Kazakhstan's security agencies. Authoritarian states such as Kazakhstan build on a personalized system of power, which make it "dangerous for presidents to resign," Schiek explained. That is why Nazarbayev ensured "he would have certain political instruments at his disposal to protect himself."

Leading Kazakhstan to independence

Nazarbayev was in power longer than any other president of a post-Soviet republic. Born to humble beginnings in 1940, he trained as a metalworker before later joining the Soviet Communist Party and quickly rising up the ranks. In the 1980s, he became prime minister and later president of the Soviet Republic of Kazakhstan. After the collapse of the Soviet Union in 1991, he led Kazakhstan to independence and remained in power.

Kazakhstan, which is roughly the size of Western Europe, managed to remain largely peaceful after gaining independence. This relative calm helped transform the resource-rich country into a major oil and gas exporter.

Strongman leader

Nazarbayev was re-elected five times, with little significant opposition. In the most recent vote in 2015, he finished with 97.7 percent support. While the Kazakh constitution officially bans anyone from serving more than two presidential terms, an exception was made for Nazarbayev.

In the final years of his reign, a veritable personality cult emerged around Kazakhstan's president. In 2010, he was officially given the title of "Elbasy" (Leader of the Nation), which guarantees him and his family legal immunity from prosecution.

Nazarbayev's reputation took a hit in 2007, when he had a falling out with his son-in-law Rakhat Aliyev, an influential lawmaker and businessman. Both accused each other of corruption. Then, in February 2015, Aliyev died while remanded in custody in Vienna. Officially, Aliyev committed suicide, though the exact circumstances of his death are unclear. Aliyev had stood accused of involvement in the murder of two bankers in Kazakhstan, and of money laundering. 

In 2011, Nazarbayev used the police to brutally suppress an oil worker strike in the town of Zhanaozen. More than 10 people died. Nazarbayev declared a state of emergency, and it took months until the situation calmed down.

Strategic alliance with Moscow

Nazarbayev always made efforts to foster close political and economic ties with Russia, as well as the West. Yet by and large, Moscow was his closest ally. In early 2015, both countries joined with Belarus to establish the Eurasian Economic Union (EAEU), one of Russian President Putin's prestige projects.

But Kazakhstan's close relationship with its larger neighbor had negative consequences, too. When the West imposed economic sanctions on Russia because of the war in Ukraine, Kazakhstan's economy took a hit as well. Kazakhstan, like Russia, struggled considerably when the price of oil fell.

Read more: Vladimir Putin's 'Crimea effect' ebbs away 5 years on

Transition to democracy unlikely

At the moment, it is unclear whether Nazarbayev resigned because of his old age, the weak economy, or popular disaffection with his rule, said Schiek. In late February, he fired and replaced the government, which Schiek called an "act of desperation."

No long term successor has been designated. Whoever it is may seek to decentralize Kazakhstan, said Schiek, though he believes it's unlikely the country will be transformed into a real democracy any time soon.