There are times when we need to be something of a ‘Spiritual Warrior’ and yet have our defences in place. A tank, as both a defensive and defended vehicle, would be likely to appear at this time in our dreams.
Psychological / Emotional Perspective:
Often in dreams we become aware of our need to overcome objections and difficulties. Sometimes the only form of expression we have is to ride roughshod over those objections. The image of a war tank helps to highlight our ability to do this without ourselves being hurt.
Everyday Material Aspects:
Dreaming of a water tank is putting ourselves in touch with our inner feelings and emotions. Dreaming of a military tank connects us with our own need to defend ourselves, but to be aggressive at the same time. Such a dream would indicate that we are feeling threatened in some way.
You might also like to consult the entries for Armed Forces, Conflict, War and Water.