12th Operational Brigade

12th Operational Brigade was a military unit of the Eastern Territorial Administration of the National Guard of Ukraine. Its history dates back to 1990, when the 129th Motorized Militia Battalion was formed in Mariupol. On January 2, 1992, the 10th Battalion of the National Guard of Ukraine was established on its basis. In 1995, the battalion was transferred to the Internal Troops of Ukraine and renamed the 17th Motorized Battalion.

On April 16, 2014, following the annexation of Crimea, servicemen of the unit repelled an attempt to seize their barracks in Mariupol.

In December 2014, the battalion was reorganized into the 18th Operational Regiment of the National Guard. Its ranks were reinforced with personnel from the Azov and Donbas battalions. In September 2016, the Donbas Battalion was transferred to the 15th Regiment stationed in Slovyansk.

In October 2019, the unit was reorganized into the 12th Brigade of Operational Assignment, with the Azov Regiment and two operational-purpose battalions under its command.

On February 24, 2022, the brigade was stationed in Mariupol and was tasked with the defense of the city. Together with other Ukrainian units, it defended Mariupol until May 20, 2022, when the remaining defenders surrendered to Russian forces at the Azovstal steel plant.

In January 2023, the Azov Regiment was expanded into the 12th Special Purpose Brigade “Azov,” formed on the basis of its former parent unit. The 12th Brigade of Operational Assignment subsequently ceased to exist.