Why did Russians end their alliance with Napoleon

Because the Russians practiced scorch and burn policy by destroying all of their crops and livestock so that the French army had nothing to eat. This made the French troops extremely weak and ill which gave the Russians the upper hand.

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Napeleon is attacking Russia to get the  land so  Russians attack back.

Explanation:

the correct answer option is: weapons.

explanation:

tensions rose as the two opposing superpowers competed for 'weapons'.

referring to the cold war (1945-1991), the two superpowers, usa and ussr, experienced a phase of struggle and conflict with each other. these two superpowers considered each other as a threat to their survival and thus opted for policies to strengthen their positions.

the two superpowers never went to war with each other directly but competed for weapons to preserve their positions.

a drastic rise in oil prices ended decades of postwar.