Losses of US Pilots and Aircraft
 12. The concentration of bombing in Route Packages
 I, II, and III, as outlined in Alternative I, would, in
 the short term, be less costly in terms of losses of US
 pilots and aircraft. This is apparent in the statistics
 for combat losses of aircraft during the first four months
 of 1967. A total of 80 US aircraft were lost during this
 period. Only 18 aircraft, or 22 percent of the total, were
 lost in combat over Route Packages I, II, and III, although
 about 70 percent of all attack sorties were flown over
 this area.
 13. When it becomes apparent to the North Vietnamese
 that the bombing is being concentrated in Route Packages
 I, II, and III and that a virtual sanctuary exists in most
 other parts of the country, they can be expected to increase
 their air defenses and to move more SAMs into the region.
 A greater defense would increase US aircraft losses although
 this area probably would never be as heavily defended as
 Route Packages VIa and VIb.
 Soviet and Chinese Responses
 14. Alternative I would substantially reduce the chances
 of increased military or political pressures on the US from
 both China and the Soviet Union. The Chinese would attribute
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