For the most part, Iraq remained on the defensive for the next five years, unable and unwilling to launch any major offensives, while Iran launched more than 70 offensives. Iraq's strategy changed from holding territory in Iran to denying Iran any major gains in Iraq (as well as holding onto disputed territories along the border). Saddam commenced a policy of total war, gearing most of his country towards defending against Iran. By 1988, Iraq was spending 40–75% of its GDP on military equipment. Saddam had also more than doubled the size of the Iraqi army, from 200,000 soldiers (12 divisions and three independent brigades) to 500,000 (23 divisions and nine brigades). Iraq also began launching air raids against Iranian border cities, greatly increasing the practice by 1984. By the end of 1982, Iraq had been resupplied with new Soviet and Chinese materiel, and the ground war entered a new phase. Iraq used newly acquired T-55, T-62 and T-72 tanks (as well as Chinese copies), BM-21 truck-mounted rocket launchers, and Mi-24 helicopter gunships to prepare a Soviet-type three-line defence, replete with obstacles such as barbed wire, minefields, fortified positions and bunkers. The Combat Engineer Corps built bridges across water obstacles, laid minefields, erected earthen revetments, dug trenches, built machinegun nests, and prepared new defence lines and fortifications.