battles being envisioned, everyone had to be placed as close to the front lines as possible. The result was a new battlefield organization that moved the vast majority of US and allied forces much closer to the border between East and West Germany, in what became known as "Forward Defense". As reinforcements from the US could play only a minor role, the war was a "come as you are" affair. Air power was key; as the battle increased in tempo and the Soviet forces attempted to break through the defenders, channels would naturally form that would be attacked by air. A 1975 study showed that: The main battle tank and attack helicopter are highly compatible weapons systems that are best employed using offensive principles where their mobility, firepower, and survivability can be optimized. The bi-dimensional mobility capabilities and overlapping firepower characteristics of the main battle tank and attack helicopter are desirable and enhance the ability to achieve a favorable exchange ratio on the battlefield. The main battle tank, complemented by the attack helicopter, will remain a decisive antlarmor weapons system for the foreseeable future. One problem that was noted soon after the introduction of the 1976 version of FM 100-5 was how to deal with the enemy's reserve forces in the rear. There was the possibility that the US could win the first battle, only to meet a second unattrited reserve force soon after. A solution to this problem was not immediately forthcoming. Military historian Gwynne Dyer also criticized the defence strategy as militarily senseless, used only because an effective defense in depth doctrine was considered politically unacceptable to West Germany since that would mean much of the country would have been overrun by Warsaw Pact forces in an invasion before they could be stopped. As a result of the political compromise, a concerted Warsaw Pact invasion would likely have been able to break through the thin defensive zone with their numerically superior conventional forces easily, which would have soon forced NATO to resort to tactical nuclear weapons to counter it, which would have likely escalated the war to a full-scale global nuclear war. Furthermore, the doctrine was considered by the Warsaw Pact to be a threatening policy, which they feared would have meant an inverted in-depth defence by NATO in an aggressive fashion which could have entailed invading the Warsaw Pact as a pre-emptive move to create the defensive