Hanoi Is Believed Shifting On Denial It Uses Troops; A SHIFT BY HANOI DETECTED BY U.S.
Amer officials see shift in N Vietnamese denial at Paris peace talks that it has troops in S Vietnam; Amb Harriman repeats Amer charges about N Vietnamese infiltration; hands to N Vietnam document giving details of enemy units and actions; N Vietnam asserts it has right to help guerrillas and pledges to do so
