explanation in the answer
The Red Scare
Central to the Cold War on the American homefront was the fear that communist spies were trying to destroy the country from within. This fear rose to a fever pitch between 1947 and 1957 during what is known as the Red Scare or the Great Fear. During this time there was a strong attempt to root out communists and communist sympathizers at all levels of society.
During this time period, the federal government and other institutions created loyalty programs. To keep their jobs, or to be hired, employees had to swear an oath of loyalty to the Constitution and to swear that they had never been a part of an organization that had advocated the overthrow of the government. They also had to swear that they would never join any such group in the future. The program went further and required hearings and investigations if someone was accused of being disloyal. Under President Truman the first loyalty program was started in 1947 - affecting federal employees and potential employees. The program soon spread to other organizations, particularly state governments, schools, and universities.
Answer:
The motivations were mostly political and were done by the communist regimes established in those countries, with purpose of detaining their political enemies.
Explanation:
In all of these countries in different period totalitarian regimes were established. As the regimes were strict they opposed every possibility of opposition in that country. The most notable example are the mentioned ones, although only in Soviet Union millions of people were killed during Stalin's regime.
It appears as though Lenin and the Bolsheviks have different ideas about "communism" compared to Marx. To begin, Lenin's communist government is considered a realization of Marx's "dictatorship of the proletariat." In addition, the Bolshevik's changed Marx's doctrines to make them fit with the new Russian realities, which explains the difference in beliefs. Lenin insisted on a full-time, professional leadership that supervised a secret party. Unlike Marx, he believed that such a party could advance the coming of the revolution and that the peasantry could be led into revolutionary action.
The Treaty of Shimonoseki required China to pay Japan for losses during the war and to give Taiwan to Japan. China was forced to fully recognized Korea's autonomy and independence, pay war indemnities to Japan and for Korea to hand Taiwan, which was then called Formosa, to Japan.