While tanks are powerful fighting machines, they seldom operate alone, being organised into armoured units in combined arms forces. Without such support, tanks, despite their armour and mobility, are vulnerable to infantry, mines, artillery, and air power. Tanks are also at a disadvantage in wooded terrain and urban environments, which cancel the advantages of the tank's long-range firepower, limit the crew's ability to detect potential threats, and can even limit the turret's ability to traverse.