When truce talks began, China spent
a year rebuilding their armies, constructing an
underground system of interconnected caves and
tunnels behind their main defensive lines, in such
strength as to be invulnerable to our artillery
except when they sent forces above ground to attack
our outposts. By July, '52, the enemy lines
were virtually impregnable, except for their own
outposts. Even in those outposts, the Chinese and
North Koreans dug deep cave systems behind their
trench lines, making any assault very costly.
Although China had only
about 500 fighters in 6/51, their air force had
grown to about 1500 MiGs by July, 1952, based in
Manchuria where Truman prevented our own air force
from attacking them. They also emplaced highly
accurate anti-aircraft guns along all approach
lines to their most vulnerable targets, making air
assault by B29's even more
hazardous.