Final answer:
In 1961, Nikita Khrushchev escalated Berlin tensions by directing the construction of the Berlin Wall, a decision that intensified the Cold War.
Step-by-step explanation:
In 1961, tensions over Berlin were escalated by then Soviet Premier Nikita Khrushchev when he opted for a dramatic and symbolic action in lieu of closing the routes between West and East Berlin. Khrushchev directed the construction of the Berlin Wall on August 13, 1961, effectively dividing the city and solidifying the ideological divide between East and West. This move came after Khrushchev's failed demands that Western powers leave West Berlin and his recognition that directly challenging U.S. President Kennedy's resolve could lead to greater conflict. The erection of the Berlin Wall halted the mass exodus of East Germans to the West and intensified the Cold War tensions, serving as a vivid representation of the so-called Iron Curtain.