Why did God bring the Roman army against Israel?

Les teaches that God brought the Roman army against Israel as an act of discipline again. He brought in the Roman army under Titus, who besieged the city. When Titus finally gained entrance, there was the greatest mayhem imaginable: the Roman legions destroyed the Jews by the thousands and took the temple down rock by rock, stone by stone, just as the prophet had written. As a result, Israel was dispersed into every nation on the face of the earth. Later, they began returning around the turn of the century, setting up kibbutzes, and eventually in 1948 Israel became a sovereign state again. Yet God is not through with the Jew, because He promised that His mercy would never depart from the nation of Israel.