How Do You Justify the Statement ?preparation for War as a Defence for Peace?

My view is the following for the last 3000 years India has been invaded by many countries. Alaxander invaded India then British ruled, French had the colony, dutch had the colony, portugese had set up colony. Why? India needs peace for its progress. When all around the nation countires have nuclear weapons India cannot sit and do tapas. Strength respects strength. Whatever we have done in defence is only to defend our freedom. At no time India either in the past or in the future would ever invade any nation and for example our nuclear policy enunciates ?no first use? . That means defending the country is the foremost mission.