Why was it difficult for Hitler to conquer the Soviet Union?

One of the most important reasons for this was poor strategic planning. The Germans had no satisfactory long-term plan for the invasion. They mistakenly assumed that the campaign would be a short one, and that the Soviets would give in after suffering the shock of massive initial defeats.

Explanation:

Violence within the borders of Mandatory Palestine between Israelis and Arabs led to an all-out civil war in 1947. This civil war ended with the establishment of the state of Israel in 1948. However, the internal conflict remains until nowadays due to the distress caused by the Sykes-Pykot Agreement, which was a secret arrangement between Britain and France to control the area known as Israel nowadays.

Arab groups such as Hamas, which are considered as terrorists by the Israelis, devote themselves to fighting off the Israelis and expelling them from a territory that they believe is legitimately theirs. These groups intentions are the main reason of the distrust by the Israelis, as they won't stop until completely expelling the Israelis from the Middle East.