In 2011 International Institute for Strategic Studies estimates that Ukraine's Air Force includes one Sukhoi Su-24M regiment, 5 regiments with Mikoyan MiG-29s and Sukhoi Su-27, one regiment with Sukhoi Su-25, two squadrons with Sukhoi Su-24MR, three transport regiments, some support helicopter squadrons, one helicopter training regiment, and some air training squadrons with L-39 Albatros. The IISS said they were grouped into the 5th and 14th Aviation Corps, the 35th Aviation Group, which is a multi-role rapid reaction formation, and a training aviation command. The IISS assesses the overall force size as 817 aircraft of all types and 43,100 personnel. The aviation corps had actually be reorganised into regional air commands in about 2004. Russian sources list three aviation groups (West, South, and Center).