President Vladimir Putin’s spokesman Dmitry Peskov told reporters that Kozak, deputy head of the Russian presidential administration, was now the most senior Kremlin official when it came to Ukraine.
Kozak, 61, was born in what used to be Soviet Ukraine.
Kozak replaces Kremlin insider Vladislav Surkov, who had overseen Russia’s ties with Ukraine and other ex-Soviet countries since 2013.
Peskov did not say whether Surkov, 55, would be leaving the Kremlin altogether but added that Kozak was now the Kremlin’s point man for Ukraine.
“In his new role Kozak is in charge and will continue to be in charge of Ukrainian issues,” Peskov told a news conference in Moscow on February 11.
Kozak is a former deputy prime minister. He was appointed deputy head of the Kremlin administration late last month.
Kozak supervised Putin’s first reelection campaign in 2004, was responsible for preparations for the 2014 Winter Olympic Games in Sochi, and served as the Kremlin’s principal person for ties with Moldova.
Relations between Moscow and Kyiv were derailed after Russia annexed Ukraine’s Crimean Peninsula in 2014 and fighting broke out between Ukrainian forces and Moscow-backed separatists in the east of the country. Russia denies any role in the conflict that has killed more than 13,000 people.
Kozak is among Russian officials who were sanctioned by the West after Russia seized Crimea.
Putin and Ukrainian President Volodymyr Zelenskiy met for the first time at a summit in Paris in December aimed at agreeing measures to help end the conflict.
The meeting was followed by a large-scale prisoner swap.
Zelenskiy on February 11 appointed a former lawyer called Andriy Yermak as his chief of staff.
Yermak, who was involved in negotiating the prisoner swaps with Russia, told Ukrainian TV on February 10 that he had met Kozak and thought he was an improvement on Surkov.