Designated as territorial defense battalion those various elements as in combat with separatist groups in the Ukraine, irregular forces fighting other irregular forces.
Among those two battalions most often mentioned in the media Azov and Donbass.
Speaking of a battalion do not think of these combat units as having a TO&E of a conventional military battalion as normally, commonly, and generally understood. Usually far less in that number of combatants, half the size of troop strength often the case.
AND UNITS OFTEN ASSOCIATED WITH THE UKRAINIAN NATIONALIST MOVEMENT DURING AND AFTER THE SECOND WORLD WAR. THE COMBATANTS OFTEN REFERRED TO AS "RIGHT WING"!!
1. "Azov fighters are Ukraine's greatest weapon and may be its greatest threat"
"The battalion's far-right volunteers' desire to 'bring the fight to Kiev' is a danger to post-conflict stability"
. . . .
"Dmitry – which he said is not his real name – is a native of east Ukraine and a member of the Azov battalion, a volunteer grouping that has been doing much of the frontline fighting in Ukraine's war with pro-Russia separatists. The Azov, one of many volunteer brigades to fight alongside the Ukrainian army in the east of the country, has developed a reputation for fearlessness in battle."
AND an American national killed while fighting with Donbass. "Franko" the nom de guerre!
2. "U.S. Army Vet Killed Fighting Pro-Russian Separatists In Ukraine"
"A graduate of the U.S. Military Academy and the only American known to have fought alongside Ukrainian forces against pro-Russian separatists has been killed in eastern Ukraine."
"Mark Gregory Paslawsky, 55, died while fighting with the volunteer Donbas Battalion."
Franko somewhat too aged to be doing the combat stuff. Age fifty-five although a graduate of the Military Academy at West Point and a graduate of the Ranger school. Franko also having lived in Ukraine for over two decades, an ethnic Ukrainian and a citizen.
3. "Territorial defense battalion (Ukraine)"
"Territorial defense battalions are volunteer paramilitary groups created in Ukraine to combat Donetsk People's Republic and Lugansk People's Republic insurgents during the War in Donbass."