We will not attack unless we are attacked, if we are attacked, we will certainly counterattack

人不犯我,我不犯人, 人若犯我,我必犯人
Ren bu fan wo, wo bu fan ren, ren ruo fan wo, wo bi fan ren
We will not attack unless we are attacked, if we are attacked, we will certainly counterattack
1970, August
Shanghaishi chuban gemingzu (上海市出版革命组)
77x106.5 cm.
BG E13/783

Soldiers at the border with the Soviet Union, believed to be a military threat to China. There actually had been a border conflict in 1969.
The text board in the image says 中国神圣領土 决不容许侵犯 (China's sacred territory can never be violated).