Gerson in his article divides occupation into three categories according to international law: invasion, belligerent occupation and post-surrender occupation and then examines the legal entry status. Invasion is when effective and continuous control over the hold areas has not yet been established. Restrictions are imposed by international law on the invader. Paragraph 4 of Article 2 of the United Nations Charter prohibits the threat or use of force during the disposition of territory. Furthermore, invaders must avoid unnecessary civilian injuries in achieving immediate military objectives. Belligerent occupation occurs when effective military control over held areas has been achieved. In this case, non-military resolutions end the war. Monitoring the population's activity and maintaining cooperation with civil society helps protect its forces. International law obliges the occupied and the occupying power to preserve the laws and institutions existing before the occupation pending demonstration that such reform was of a minor nature, necessitated by public order, security needs or humanitarian considerations . Post-surrender occupation is a continuous occupation of territory after the unconditional surrender of the enemy and his allies. International law guarantees the occupier broad administrative freedom after surrender. After all, the enemy has been defeated and has little or no bargaining power to influence land management. The following section examines justifications for assuming lawful entry status: Self-defense can be lawful entry. Article 51 of the United Nations Charter provides that “nothing in this Charter shall affect the inherent right of individual or collective self-defense IF an armed attack occurs against a … means of paper … on planning for the future of Iraq. Some lessons from the British experience: Never assume that liberated people will be grateful that their country has been conquered, even if a hated autocrat has been removed. Be careful what you ask for. The United States should consider the different types of ideologies present in Iraq and then choose whether to bring democracy to Iraq or maintain US strategic interests. Beware of unintended consequences, such as the creation of sectarian and ethnically segregated education systems, the remaking of the military and military, and debt payments that cause repair costs, previous debt, and new debt. Never impose a system that cannot be protected or defended. For example, due to the invasion economic and political problems would appear so that the US would not be able to protect the system and US supporters would no longer be interested in staying in Iraq.