A casing cutting tool, to be disposed downhole in a casing string on a drillstring, for the cutting and/or milling of casing strings. The tool has a main body with a plurality of rotatable blades which can rotate between a first retracted position to a second position substantially at right angles to the main body. In this second position, cutting surfaces on the blades engage the casing wall, and rotation of the tool results in cutting of the casing. A plurality of stabilizing arms are rotatably attached to the main body. A link between the blades and the stabilizing arms forces the stabilizing arms to rotate outward when the blades rotate outward. The stabilizing arms are dimensioned to span the inner diameter of the casing string, while leaving clearance to rotate the tool. The outermost ends of the stabilizing arms are rounded to avoid cutting the casing and reduce drag.