USSR puzzle

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Across
  1. 2. part of USSR/Russia surrounded by Baltic Sea, Belarus and Poland
  2. 4. USSR leader during Cuban Missile Crisis
  3. 5. breed of dog developed by USSR
  4. 6. name of dog the USSR sent to space
  5. 8. known as Leningrad under the USSR
  6. 9. US president during Cuban Missile Crisis
  7. 10. site of the siege that lasted 5 months during WW2
Down
  1. 1. USSR stands for this
  2. 3. site of nuclear disaster in 1986
  3. 7. last Supreme Leader of the USSR