With the militarisation of aeroplane, air threat emerged as a new dimension of warfare. It assumed serious proportions once the bombs were unleashed upon the unsuspecting population. By Second World War, bombing from air became key to victory. It also resulted in death to millions, both military and civil. The cataclysmic destruction by atom bombs over Hiroshima and Nagasaki eventually gave way to the Doctrine of Mutual Assured Destruction. It meant that nuclear arsenal was only to deter but not to be used. Because the use of large number of nukes at one time totaling around 30,000 would have meant a certain end to mankind. Info the above spectre of threat, new offensive weapons in the from of conventional missiles, armed UAV’s, cruise missiles, antiship missiles, stand off precision weapons and cyber attacks have been added in the last few decades. Threat from air has widened in scope and become even more decisive in outcome of conflicts. Air Defence too evolved along with newer in threats; often in compartments. But the current threats demand a more comprehensive and cohesive air defence, both, for defence effectiveness as well as cost effectiveness. This book is an analytical study towards this goal.