nickname "Russian Woodpecker". The idea that any nuclear conflict would eventually escalate was a challenge for military strategists. This challenge was particularly severe for the United States and its NATO allies. It was believed (until the 1970s) that a Soviet tank offensive into Western Europe would quickly overwhelm NATO conventional forces, leading to the necessity of the West escalating to the use of tactical nuclear weapons, one of which was the W-70. This strategy had one major (and possibly critical) flaw, which was soon realized by military analysts but highly underplayed by the U.S. military: conventional NATO forces in the European theatre of war were far outnumbered by similar Soviet and Warsaw Pact forces, and it was assumed that in case of a major Soviet attack (commonly envisioned as the "Red tanks rolling towards the North Sea" scenario) that NATO—in the face of quick conventional defeat—would soon have no other choice but to resort to tactical nuclear strikes against these forces. Most analysts agreed that once the first nuclear exchange had occurred, escalation to global nuclear war would likely become inevitable. The Warsaw Pact's vision of an atomic war between NATO and Warsaw Pact forces was simulated in the top-secret exercise Seven Days to the River Rhine in 1979. The British government exercised their vision of a Soviet nuclear attack with Square Leg in early 1980. Large hardened nuclear weapon storage areas were built across European countries in anticipation of local US and European forces falling back as the conventional NATO defense from the Soviet Union, named REFORGER, was believed to only be capable of stalling the Soviets for a short time. 1980s In the late 1970s and, particularly, during the early 1980s under U.S. President Ronald Reagan, the United States renewed its commitment to a more powerful military, which required a large increase in spending on U.S. military programs. These programs, which were originally part of the defense budget of U.S. President Jimmy Carter, included spending on conventional and nuclear weapons systems. Under Reagan, defensive systems like the Strategic Defense Initiative were emphasized as well. Another major shift in nuclear doctrine was the development and the improvement of the submarine-launched, nuclear-armed, ballistic missile, or SLBM. It was hailed by many military theorists as a weapon that would make nuclear war less likely. SLBMs—which can move with "stealth" (greatly lessened detectability) virtually anywhere in the world—give a nation a "second