There is conditioning on both sides. The US has traditionally been more sophisticated at this than PRC, but the latter are catching up.
Access to "sensitive" historical records was never allowed. Even some records from the 19th century, like the archives of the Chinese Maritime Customs Service were denied. And with the advent of the campaign against "historical nihilism" things have become much more difficult for foreign historians:
Besides, the West does have a tradition of writing history to attack their adversary, starting all the way from Herodotus. Even as the West is right now using their propaganda machine and education system to gradually downplay and eventually wipe out the USSR's contribution to the defeat of the Axis. And they are doing this under the disguise of "academic freedom". Campaign against historical nihilism is essential and important in preventing politically motivated academics turning into total historical revisionists.