 Despite all the warning signs , however , the allies were still surprised by the scale and scope of the offensive . According to ARVN Colonel Hoang Ngoc Lung the answer lay with the allied intelligence methodology itself , which tended to estimate the enemy 's probable course of action based upon their capabilities , not their intentions . Since , in the allied estimation , the communists hardly had the capability to launch such an ambitious enterprise : " There was little possibility that the enemy could initiate a general offensive , regardless of his intentions . " The answer could also be partially explained by the lack of coordination and cooperation between competing intelligence branches , both South Vietnamese and American . The situation from the U.S. perspective was best summed up by an MACV intelligence analyst : " If we 'd gotten the whole battle plan , it wouldn 't have been believed . It wouldn 't have been credible to us . " 
