Why did the USA-USSR alliance begin to break down towards the end of WWII?

The USA-USSR alliance break down.

Explanation:

There are several reasons for the breaking of the alliance between the USA and the USSR.  Both countries tried to keep their position among world power. Both their plans led to an increase in concern and suspicion. Another reason was the United States government hostile towards the Soviet leader and opposed to a state ideologically based on communism.

honestly it just comes down to the

answer: secession

secession, as it applies to the outbreak of the american civil war, comprises the series of events that began on december 20, 1860, and extended through june 8 of the next year when eleven states in the lower and upper south severed their ties with the union. the first seven seceding states of the lower south set up a provisional government at montgomery, alabama. after hostilities began at fort sumter in charleston harbor on april 12, 1861, the border states of virginia, arkansas, tennessee, and north carolina joined the new government, which then moved its capital to richmond, virginia. the union was thus divided approximately on geographic lines. twenty-one northern and border states retained the style and title of the united states, while the eleven slave states adopted the nomenclature of the confederate states of america.

explanation: