Roosevelt was convinced Stalin wouldn't annex land
Of course the west simply thought the Russians were grabbing land in a quest for world domination , but there were more practical reasons behind the occupying of Poland and other countries....
The Soviet union had suffered huge numbers of killed and wounded in the war , and total destruction of many cities , far higher than any other country in the war..
Comrade Stalin decided that if there was going to be another European war , the Russians were going to fight it in Poland , Rumania , East Germany etc not in the Soviet union...