For the battle, the Russians used three armies along with a tank division and a rocket artillery brigade. By mid-April, Russia had concentrated upwards of 65 battalion tactical groups (BTGs) on the line of contact. Over the course of several days before 18 April, 11 BTGs were added to the existing Russian strength in the Donbas, bringing the total number of BTGs in the Donbas to 76, amounting to a total of about 60,000 troops.[39][40] Additionally, 22 BTGs (constituting about 15–20,000 soldiers) were said to be being resupplied and reinforced to the north of Ukraine.