The Merkava series of main battle tanks is developed and manufactured by Israel Military Industries, Ltd for the Israel Defense Forces. It is designed to ensure crew survival, battle perseverance, and quick revival in case of bad damage, though it is still is vulnerable to remotely operated land mines. The heavily shielded engine is placed at the front of the tank, while the crew is able to escape through doors at the rear. When and why did Israel decide to develop the Merkava? Discuss