Related Rule
United States of America
Practice Relating to Rule 24. Removal of Civilians and Civilian Objects from the Vicinity of Military Objectives
The US Air Force Pamphlet (1976) states:
As a corollary to the principle of general civilian immunity, the parties to a conflict should, to the maximum extent feasible, take necessary precautions to protect the civilian population, individual civilians, and civilian objects under their authority against the dangers resulting from military operations. Accordingly, they should endeavor to remove civilians from the proximity of military objectives … It is incumbent upon states, desiring to make protection of their own civilian population fully effective, to take appropriate measures to segregate and separate their military activities from the civilian population and civilian objects. Substantial military advantages may in fact be acquired by such separation. 
United States, Air Force Pamphlet 110-31, International Law – The Conduct of Armed Conflict and Air Operations, US Department of the Air Force, 1976, § 5-4(a).
The US Naval Handbook (1995) states:
A party to an armed conflict has an affirmative duty to remove civilians under its control as well as the wounded, sick, shipwrecked, and prisoners of war from the vicinity of targets of likely enemy attacks. 
United States, The Commander’s Handbook on the Law of Naval Operations, NWP 1-14M/MCWP 5-2.1/COMDTPUB P5800.7, issued by the Department of the Navy, Office of the Chief of Naval Operations and Headquarters, US Marine Corps, and Department of Transportation, US Coast Guard, October 1995 (formerly NWP 9 (Rev. A)/FMFM 1-10, October 1989), § 11.2.
The US Naval Handbook (2007) states: “A party to an armed conflict has an affirmative duty to remove civilians under its control (as well as the wounded, sick, shipwrecked, and prisoners of war) from the vicinity of objects of likely enemy attack.” 
United States, The Commander’s Handbook on the Law of Naval Operations, NWP 1-14M/MCWP 5-12.1/COMDTPUB P5800.7, issued by the Department of the Navy, Office of the Chief of Naval Operations and Headquarters, US Marine Corps, and Department of Homeland Security, US Coast Guard, July 2007, § 8.3.2.
In 1972, the General Counsel of the US Department of Defense stated:
The principle [contained in paragraph 1(c) of UN General Assembly Resolution 2444 (XXIII) of 1969 that a distinction must be made at all times between persons taking part in the hostilities and members of the civilian population to the effect that the civilians be spared as much as possible] addresses primarily the Party exercising control over members of the civilian population. This principle recognizes the interdependence of the civilian community with the overall war effort of a modern society. But its application enjoins the party controlling the population to use its best efforts to distinguish or separate its military forces and war making activities from members of the civilian population to the maximum extent feasible so that civilian casualties and damage to civilian objects incidental to attacks on military objectives, will be minimized as much as possible. 
United States, Letter from J. Fred Buzhardt, General Counsel of the Department of Defense, to Senator Edward Kennedy, Chairman of the Subcommittee on Refugees of the Committee on the Judiciary, 22 September 1972, AJIL, Vol. 67, 1973, p. 123.
In 1991, in response to an ICRC memorandum on the applicability of IHL in the Gulf region, the US Department of the Army stated:
The obligation of distinguishing combatants and military objectives from civilians and civilian objects is a shared responsibility of the attacker, defender, and the civilian population as such. An attacker must exercise reasonable precautions to minimize incidental or collateral injury to the civilian population, consistent with mission accomplishment and allowable risk to the attacking force. A defender must exercise reasonable precaution to separate the civilian population and civilian objects from military objectives. Civilians must exercise reasonable precaution to remove themselves from the vicinity of military objectives or military operations. The force that has control over the civilians has an obligation to place them in a safe place. 
United States, Message from the Department of the Army to the legal adviser of the US Army forces deployed in the Gulf, 11 January 1991, § 8(E), Report on US Practice, 1997, Chapter 1.7.
In 1992, in its final report to Congress on the conduct of the Gulf War, the US Department of Defense stated:
Historically, and from a common sense standpoint, the party controlling the civilian population has the opportunity and responsibility to minimize the risk to the civilian population through the separation of military objects from the civilian population, evacuation of the civilian population from near immovable military objects, and development of air raid precautions … The defending party must exercise reasonable precautions to separate the civilian population and civilian objects from military objectives, and avoid placing military objectives in the midst of the civilian population. 
United States, Department of Defense, Final Report to Congress on the Conduct of the Persian Gulf War, 10 April 1992, Appendix O, The Role of the Law of War, ILM, Vol. 31, 1992, p. 625.
In the report, the Department of Defense accused Iraq of having violated its obligations:
Iraqi authorities elected not to move civilians away from objects they knew were legitimate military targets, thereby placing those civilians at risk of injury incidental to Coalition attacks against these targets, notwithstanding the efforts by the Coalition to minimize risk to innocent civilians … The Government of Iraq elected not to take routine air-raid precautions to protect its civilian population. Civilians were not evacuated in any significant numbers from Baghdad, nor were they removed from proximity to legitimate military targets. There were air raid shelters for less than 1 percent of the civilian population of Baghdad … The Government of Iraq was aware of its law of war obligations. In the month preceding the Coalition air campaign, for example, a civil defense exercise was conducted, during which more than one million civilians were evacuated from Baghdad. No government evacuation program was undertaken during the Coalition air campaign. 
United States, Department of Defense, Final Report to Congress on the Conduct of the Persian Gulf War, 10 April 1992, Appendix O, The Role of the Law of War, ILM, Vol. 31, 1992, pp. 623 and 625–626.
In 1993, in its report to Congress on the protection of natural and cultural resources during times of war, the US Department of Defense stated:
The obligation to take reasonable measures to minimize damage to natural resources and cultural property is shared by both an attacker and a defender … The defender has certain responsibilities as well, not the least of which is to take all reasonable measures to separate military objectives from civilian objects and the civilian population. Regrettably, in conflicts such as the Korean and Vietnam Wars, as well as the 1991 Persian Gulf War, the armed forces of the United States have faced opponents who have elected to use their civilian populations and civilian objects to shield military objectives from attack. Notwithstanding such actions, U.S. forces have taken reasonable measures to minimize collateral injury to civilians and damage to civilian objects while conducting their military operations, often at increased risk to U.S. personnel. 
United States, Department of Defense, Report to Congress on International Policies and Procedures Regarding the Protection of Natural and Cultural Resources During Times of War, 19 January 1993, p. 203.
The Report on US Practice states:
It is the opinio juris of the United States that parties to a conflict should, to the maximum extent feasible, segregate and separate their military activities from the civilian population to protect the latter. Alternatively, where feasible, it may be necessary to remove civilians from the vicinity of military operations in order to protect them from the effects of attacks. 
Report on US Practice, 1997, Chapter 1.7.