A Timely Correction

As far as I know, the PRC has never retracted, or re-examined, its claims that UN forces in Korea during the Korean war used bacteriological and/or chemical weapons. This is a pity because evidence that has come out since the collapse of the USSR puts it beyond doubt that this never, ever happened. As the USSR council of ministers itself resolved on the 2nd of May, 1953 (after Stalin's death):

For Mao Zedong

"The Soviet Government and the Central Committee of the CPSU were misled. The spread in the press of information about the use by the Americans of bacteriological weapons in Korea was based on false information. The accusations against the Americans were fictitious."

To give recommendations:
To cease publication in the press of materials accusing the Americans of using bacteriological weapons in Korea and China.

To consider it desirable that the Government of the PRC (DPRK) declare in the UN that the resolution of the General Assembly of 23 April about investigating the facts of the use by the Americans of bacteriological weapons on the territory of China (Korea) cannot be legal, since it was made without the participation of representatives of the PRC (DPRK). Since there is no use of bacteriological weapons, there is no reason to conduct an investigation.

In a tactical way to recommend that the question of bacteriological warfare in China (Korea) be removed from discussion in international organizations and organs of the UN.

Soviet workers responsible for participation in the fabrication of the so-called "proof" of the use of bacteriological weapons will receive severe punishment." 

Every so often there is speculation that the CCP may, for example, decide to rehabilitate politicians who at various times had unjustly fallen foul of the historical CCP leadership, most often it is those behind the Tiananmen demonstrations are discussed in these terms. However, this is yet to ever happen, since it is painfully difficult for the CCP leadership to allow admission that it ever failed or was wrong about anything - in fact, since Deng's era it is hard to think of anything new beyond the admission that Mao was wrong an (undefined) 30% of the time that constitutes an admission of failing.

Perhaps something like the Tiananmen square demonstrations is still too recent, and too painful an incident for the Chinese authorities to reopen, but if something now as distant and uncontroversial as the CCP's long-abandoned (and not now taken seriously by anyone) claims of biological warfare in the Korean war cannot finally be admitted as fake, then it is hard to ever conceive of what might be admitted as a mistake beyond the generic admissions of failings during the Mao era. This inability to admit failing creates an ever growing number of controversies which the CCP denies even exists, and an ever-growing list of people aware of these controversies. This attempt to create a "country without history" cannot continue forever.

[Picture: A Korean-war-era Chinese Communist propaganda poster]