" By contrast , the bombing of North Vietnam was restricted , especially during the first two years of Operation Rolling Thunder ( 1965 - 1966 ) . And LBJ did micromanage the air war in the North , once bragging , " I will not let those Air Force generals bomb the smallest outhouse north of the seventeenth parallel without checking with me . " His personal oversight was based on one overriding fear : that a more aggressive campaign against North Vietnam might compel the Chinese , or even the Soviets , to enter the war . Johnson well recalled how 300,000 Chinese troops poured into Korea after the United States attacked past the 38th parallel and fought all the way up to the Chinese border . "
" A gradual escalation of the bombing , LBJ believed , would prevent China from intervening . Explaining his reasoning to journalists , he said U.S. bombing was " seduction , not rape . " Only ' rape , ' he claimed , was likely to draw China into the war . When Senator George McGovern met Johnson in 1965 to express concerns about possible Chinese intervention , LBJ told him not to worry : " I am going up her leg an inch at a time .... I will get to the ' snatch ' before they know what is happening . "