Jr'.ited States vould not necessarily meet mi_litary a.ction where it occurred, butnight respond, vith or vithout nucl-ear weapons, with attacks on strategic targets. 30?. The Soviet Union's first thermonuclear test in f953 and the launching of tbefirst Soviet Sputnik in 195? ended the American monopol-y of thexmonuclear weapons €nd niade it ctear that the United States would thenceforth be within "ange ofint,ercontinentaf nissiles. These two advances of Soviet technology - particuJ_arlytbe latter - had a great psychological inpact in the United States at the tine. 308. ?he increased vulnerability of the United States put an end to the id.ea of thetraditional- rttr'ortress Americatt. For the first tine in this century there Lras aserious rnilitary threat to the United States mainland. The intloduction oftactical nuclear weapons in the late f950s and the emergence of the concept oflini.ted warfare were tvo converAent factors of readiustment at the level ofrnilitary doctrines " 309" Thus, impo"tart changes in the nuelear doetrines of the United States tookplace in the beginni.ng of the 1960s and the doctrine of ftexible response was announced. The concept of linitation vas underl-ined in the selection of available means, for fear that a general-ized var would 1ead. to nutual- suicide, 310. At the ]evel of limited warfare, greater stress L'as placed on strengtheningthe conventional forces of the NATO a1l-iance. Earlier the United States had relied on the threat of massive retaliation to protect itself" but that doctrine vas considered to have lost much of its credibility in the face of the developmentsnd st"engthening of the Soviet Unionrs nuclear panoply. The viev lras nori' that thestrategic forces of each side would act a6 a shield behind wbieh its conventionalforces could, if need be, carry on a liroited var. The conventional^ forces should be abLe to act as a "stopping nechanismrl or impose a "pause" in the outbleak ofhostilities. 33/ The strengthening of conventional forces was said to ain at
**Analysis**
The text appears to be discussing the military strategies and doctrines of the United States and the Soviet Union during the Cold War era. It highlights the impact of Soviet technological advancements on American military thinking, the shift from a policy of massive retaliation to a doctrine of flexible response, and the emphasis on strengthening conventional forces. The text does not mention economic, social, or cultural aspects, but rather focuses on military and strategic developments.

**Category**
Science and technology, Defense