Do you think the formation of Nato and the Warsaw Pact increased or decreased tensions between the U. S and the Soviet Union

No. Creating of NATO and Warsaw Pact shifted the tension between the two on the military level. Now, conflict was not only political and ideological but also military.

Explanation: At that time people were not able to solve problems in a non-aggressive way. Invention of atomic bomb was viewed as a way how to secure peace but it did not lead to mutual understanding, tolerance and confidence. The atmosphere of lack of confidence continued, and got perhaps even worse. On the other hand, experience with WW II was an important lesson ...both powers did not want to risk.

the viking voyages took place during the middle ages, which was about this time. 500 to 1350. the viking voyages took place during the middle ages, which was about this time.