Final answer:
The economic policy that Lenin started and Stalin halted was the New Economic Policy (NEP), which introduced limited capitalist elements but was discontinued in favor of Stalin's Five-Year Plans and collectivization efforts.
Step-by-step explanation:
Economic Policies during Lenin and Stalin's Tenure
The economic policy initiated by Vladimir Lenin and later halted by Joseph Stalin was the New Economic Policy (NEP). The NEP was introduced in 1921 as a means to address the severe economic dislocations caused by World War I and the subsequent civil war. Under Lenin, the policy relaxed the more draconian features of war communism, allowing for a limited reintroduction of capitalist elements, such as permitting peasants to sell their produce on the market and authorizing the operation of small private businesses, albeit while keeping the government in overall control of the economy.
However, after Lenin's death in 1924, Stalin eventually rose to power and decisively ended the NEP. Stalin viewed the policy as a temporary retreat from the ideals of socialism and by 1928 he introduced the first of his Five-Year Plans, focusing on rapid industrialization and collectivization of agriculture. This shift marked a move towards a command economy and a significant intensification of state control over all aspects of life, diverging greatly from the relative economic freedoms under the NEP.
The termination of the NEP by Stalin led to dramatic economic and social changes, like the collectivization that resulted in the tragic Ukrainian famine known as the Holodomor. Stalin's economic strategies diverged distinctly from Lenin's NEP, as they entirely rejected capitalist elements and enforced state control, fulfilling his autocratic vision for the Soviet Union's future.