of the US bombing program. Although the mining of some North
 Vietnamese waterways has reduced the movement of large craft,
 small boat traffic continues. The increase in boat construction
 throughout North Vietnam and a program of waterway improvement
 indicate that the Communists intend to exploit further the
 potentialities of these water routes. In Laos, there has been
 increased use of small pirogues and motorboats on rivers over
 the last year. The use of these waterways will probably continue
 to increase.
 18. Rail. The North Vietnamese also use the rail line south
 of Hanoi for movement of supplies into MR-4. Despite repested US
 air attacks, the North Vietnamese have been able to construct
 bypasses and keep sections of the line serviceable from Hanoi to
 Vinh. South of Vinh the rail line is not operable for regular
 rail equipment. The North Vietnamese can only use light gear,
 principally trucks with converted wheels, to transport supplies
 over the remaining rail segment in this area.
 19. Impact of Air Attacks. Air attacks in North Vietnam,
 Laos, and the DMZ have destroyed trucks, railroad rolling stock,
 -17-
 
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