In the offense, the chief function of Soviet combat engineers is to assist in maintaining high rates of combined arms mobility on the battlefield, which is the premier tactical principle of threat military doctrine. Emphasis is placed on clearing and maintaining routes for the advance of combined arms units, to include breaching or removing mines and obstacles, crossing water obstacles, and assisting in flank protection or protection against counterattack. Engineer reconnaissance, independently or in collaboration with other reconnaissance means, plays a significant role in facilitating movement. Camouflage and protection during halts or temporary assumption of the defense are also basic engineer functions.