The Azeris initiated a new offensive on 1 January 1993, successfully cutting the Lachin corridor the following day and isolating Armenian forces in Nagorno-Karabakh from resupply from Armenia proper. The Armenian Air Force helped bring up reinforcements for a counterattack that began 7 January. The first day of this action, the Armenian Air Force suffered its worst single-day losses with an Mi-8, Mi-24 and a (possibly Russian) Su-25 shot down; the Su-25 may have been brought down by friendly fire. By the time the Azeri attack had been defeated at the end of the month, another three helicopters and possibly another fighter – reportedly a MiG-21 (and therefore probably Russian) – were lost.