The correct answer is the Berlin Wall.
The Berlin Wall was built in 1961 in order to separate West Berlin, which was controlled by the US, France, and Great Britain, from East Berlin (which was controlled by the Soviet Union). This wall split up families and became a significant piece of symbolism during the Cold War era. This wall symbolized the stark differences between the United States and Soviet Union on how a society should be run, as East and West Berlin were run in two completely different ways.
Republican politician Theodore Roosevelt unexpectedly became the 26th president of the United States in September 1901, after the assassination of William McKinley. Young and physically robust, he brought a new energy to the White House, and won a second term on his own merits in 1904.
To limit the power of the russian empire in the balkans
During the interwar period, the United States adopted an 'isolation' policy. The rationale behind this policy was to avoid being sucked into another European war, as the US had done in WW1. The policy was ultimately abandoned with the rise of Hitler and the attack on Pearl Harbour in 1941.
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