The list is too long to count, but the Berlin Blockade, the Bay of Pigs, the Cuban Missile Crisis, Gary Powers' U-2 shoot-down and KAL 007 all severely strained US-Soviet relations.
The Cold War.
The Battle of Fort Sumter.
the Boston Massacre
The bombardment of Fort Sumter started the Civil War
The event that marked the end of Spain's rivalry with England was the English navy defeating the Spanish Armada. It is most famous event tat happened in English history.
break up of the Soviet Union
the soviet union launched the satellite sputnik l
The Battle of Fort Sumter.
the Boston Massacre
It marked the start of the space race between the U.S. and U.S.S.R.
The lanching of Sputnik.
Leo III changing the law about icons
Leo III changing the law about icons
The bombardment of Fort Sumter started the Civil War
The bombardment of Fort Sumter started the Civil War
The bombardment of Fort Sumter started the Civil War
The collapse of the Soviet Union led to the economic crisis of 1991 in Cuba. This was due to the close ties between Cuba and the Soviet Union.
who, what, where, and why? what time area causes tension. that needs more detail to be answered.