Kazakh President Nursultan Nazarbaev was sworn in to his fifth term on April 29, just three days after his landslide victory in an election criticized by international observers.
Nazarbaev, 74, took the oath of office with his right hand on Kazakhstan's constitution at the Palace of Independence in Astana.
Nazarbaev took his oath in Kazakh but his inauguration speech was in Russian.
In the speech, he said the energy-producing Central Asian nation would continue to seek a balance in its foreign policy.
"We will continue to develop ties with our strategic partners -- Russia, the People's Republic of China, the United States of America, the European Union, and the Islamic world," he said.
The inauguration followed unusually quickly after the April 26 election, and came a day after Nazarbaev was officially declared the victor with 97.75 percent of the vote in the nation of 18 million.
Observers from the Organization for Security and Cooperation in Europe (OSCE) said that "voters were not offered a genuine choice" in the election.
Nazarbaev has ruled since 1989, two years before Kazakhstan gained independence in the breakup of the Soviet Union.
Critics say he has maintained power by sidelining opponents, suppressing dissent, and engineering his exception from presidential term limits -- enabling him to seek to stay in office for life if he chooses.
Listing what he said were the five main external "challenges" Kazakhstan faces as he enters his five-year term, Nazarbaev put "new non-system players who use extremism and violence" at the top -- an apparent reference to Islamic State and other extremist groups.
Among other challenges, he listed global economic turbulence, "trade wars," and the risk of Kazakhstan being affected by new global dividing lines.
Kazakhstan's economy has suffered lately from the effects of last year's plunge in oil prices and Western sanctions against Russia, its northern neighbor and partner in a customs union, over Moscow's interference in Ukraine.
The presidential election had been scheduled for 2016, but it was moved up to April 26 after a national assembly chaired by Nazarbaev decided it should be held early to "ensure the continuity of the current policy."
In an article published ahead of the vote, Nazarbaev said the election would give the elected president a clear mandate to lead the country through potentially troubled times.
The election is widely believed to have been moved up to quash any speculation about a successor and eliminate the risk that economic troubles could have become severe enough to hurt his chances of recording a convincing victory.
Nazarbaev also said climate change and the threat of natural disasters was a challenge.
Hours after the inauguration ceremony, Nazarbaev reappointed Karim Masimov as Kazakhstan's prime minister.
He signed a decree on Masimov's reappointment after lawmakers unanimously approved the choice.
Masimov, 49, has been prime minister since April 2014 and also held the post in 2007-2012.