The department of industry controls all the affairs related to industry, whether they pertain to heavy industry like manufacturing of motors, engines, vehicles, materials, electrical equipment, or light industry. Whether those factories are public property, or individual property that has a relationship with military industries, all of them have to be based on the war policy. Jihad and fighting require an army. In order that the army can fight it requires weapons. In order that these weapons be of the highest level and fully available, it is necessary to have industry within the state. Therefore, the military industry has a strong relation with Jihad and is closely linked to it.

In order that the state is independent of other countries and not influenced by anyone of them, it should carry out the manufacture and development of its own weapons by itself. This makes it independent and in continuous possession of the most advanced and strongest weaponry, regardless of the level of development and advancement of weapons. It would also have at its disposal, all that it needs of weapons to intimidate every apparent and potential enemy as Allah (swt) says;

“Make ready for them all you can of (armed) force and of horses tethered, that thereby you may dismay the enemy of Allah and your enemy, and others beside them whom you know not. Allah knows them.” [TMQ 8:60]

As such, the state would have its own will, produce the weapons that it needs and develop them continuously so that it owns the strongest and most developed weapons in order to terrify all the apparent and potential enemies. Therefore, it is a duty upon the state to manufacture weapons by itself and it is not allowed for her to depend upon other states, because this allows other states to control it, its will, its weapons and its fighting.

The states that sell weapons to other states do not readily sell every weapon, particularly the most developed weapons. They do not sell weapons except with certain conditions that include their utilisation. They will not sell them except in certain quantities that they, rather than the purchasing countries, decide. This gives the state that sells arms, authority and influence over the state that buys the arms enabling it to enforce its own will on the purchasing state, particularly if it was involved in a war. In that case it would need more arms, spare parts, and ammunition, which would increase its dependence on the state that exports its arms and ensure submission to its demands. This allows the state which exports arms to control it and its will, especially in times of war and in times of great need for arms and spare parts. Hence, such a state would make itself, its will and its entity hostage to the state that exports arms to it.

Therefore, for all these reasons, the state has to carry out by itself the manufacture of its own arms and everything it requires for its war machine and spare parts. This can’t be achieved unless the state possessed heavy industry and started to build factories that produce heavy industry, both the military and the non-military alike. Thus it is necessary that the state has factories for producing all types of atomic bombs, rockets, satellites, aeroplanes, tanks, spacecraft, mortars, naval ships, armoured vehicles, and all types of heavy and light weapons. It is necessary that it has factories which produce machines, motors, materials, and electronics and factories which have relation with public property and light factories which have relation with the military or war industries. All this is required by the duty of preparation that is obliged upon the Muslims by the saying of Allah (swt):

“Make ready for them all that you can of (armed) force.” [TMQ Al-Anfal: 60]

Since the Islamic state conveys the message of Islam by Da’wa and Jihad, it should be a state that should be continually ready to carry out Jihad. This requires the existence of heavy and light industry built upon the basis of war policy. This is because, at any time it requires to transform these factories for military purposes, it is easily done. Therefore, all the industry in the Khilafah state should be based on war policy, and all the factories, which produce the light and heavy industries, should be based on this policy, so that it becomes easy to transform their production to military production at any time the state requires.