So too, unfortunately, did the positions of the truce negotiators, who were unable to make any progress on the peace front during the summer. The chief stumbling block was the inability of the parties to agree on a cease-fire line. The Communists argued for a return to the status quo ante- that is, that the two armies withdraw their forces to the prewar boundary line along the 38th Parallel. This was not an unreasonable position, since the combat lines were not all that far from the 38th Parallel. The UN, however, refused to agree to a restoration of the old border on the grounds that it was indefensible in many places. Current UN positions were much more defensible, and a more defensible border was clearly advantageous, not only in protecting South Korea in the present conflict, but in discouraging future Communist aggression. Consequently, UN negotiators argued in favor of adopting the current line of contact as the cease-fire line.