Pope Benedict XVI in his new book Jesus of Nazareth: Holy Week: From the Entrance Into Jerusalem To The Resurrection (Ignatius, 2011)(which is smaller than I expected (more compact)) writes the following regarding the “triumphal entry”:
For now let us note this: Jesus is indeed making a royal claim. He wants his path and is action to be understood in terms of Old Testament promises that are fulfilled in his person. The Old Testament speaks of him – and vice versa: he acts and lives within the word of God, not according to projects and wishes of his own. His claim is based on obedience to the mission received from is Father. His path is a path into the heart of God’s word. At the same time, through this anchoring in the text in Zechariah 9:9, a “Zealot” exegesis of the kingdom is excluded: Jesus is not building on violence; he is not instigating a military revolt against Rome. His power is of another kind: it is in God’s poverty, God’s peace, that he identifies the only power that can redeem (5).