Doncaster is to cut all ties with its twin town of Ozyorsk following the Russian invasion of Ukraine.
Mayor Ros Jones said she planned to end the agreement "in outrage to the actions of the Russian President Vladimir Putin".
The two towns were linked in the 1990s following the fall of the Soviet Union.
Doncaster is the second council in Yorkshire to take action after Wakefield announced plans to sever links to Belgorod on Monday.
Ozyorsk has a population of 90,000 and lies about 1,100 miles (1,800km) to the east of Moscow.
Mrs Jones said: "Doncaster stands with Ukraine during this difficult time, and anything that we think is difficult in this country pales into insignificance when we see what the people of Ukraine are now having to endure."
She also announced Doncaster's Mansion House, library and museum would be lit up in the blue and yellow colours of the Ukrainian flag, according to the Local Democracy Reporting Service.
In a speech to councillors, she said: "My sympathy goes out to the people of Ukraine. It's the innocent men, women and children who will be the biggest victims of this war.
"I trust that Western allies can find ways and means of freeing the people of Ukraine from this oppression, and that the people of Ukraine can once again enjoy the freedom that they deserve, away from tyranny and terror."