The UK government has added Sergei Vladimirovich Yeliseyev to its list of sanctioned individuals.

The 51-year-old is the deputy prime minister of the Russian exclave of Kaliningrad, as well as “head of the Russia-backed government in the temporarily controlled territory of Kherson,” according to the entry added to the UK government’s sanctions list on Tuesday.

Yeliseyev is “involved in destabilizing Ukraine or undermining or threatening the territorial integrity, sovereignty or independence of Ukraine,” the UK government says.

Ukraine’s southern Kherson region, which Russia has claimed to annex, is only partially controlled by Russian forces. The Ukrainian military has been making significant advances in that region in recent days.