Règle correspondante
United States of America
Practice Relating to Rule 8. Definition of Military Objectives
Section I. Presence of civilians within or near military objectives
The US Naval Handbook (1995) states:
Deliberate use of noncombatants to shield military objectives from enemy attack is prohibited. Although the principle of proportionality underlying the concept of collateral damage and incidental injury continues to apply in such cases, the presence of non-combatants within or adjacent to a legitimate target does not preclude attack of it … Unlike military personnel (other than those in a specially protected status such as medical personnel and the sick and wounded) who are always subject to attack whether on duty or in a leave capacity, civilians, as a class, are not to be the object of attack. However, civilians that are engaged in direct support of the enemy’s war-fighting or war-sustaining effort are at risk of incidental injury from attack on such activities. 
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 and 11.3.
The US Naval Handbook (2007) states:
Although the principle of proportionality underlying the concept of collateral damage continues to apply in such cases, the presence of civilians within or adjacent to a legitimate military objective does not preclude attack of it. Such military objectives may be lawfully targeted and destroyed as needed for mission accomplishment. In such cases, responsibility for the injury and/or death of such civilians, if any, falls on the belligerent so employing them.
The presence of civilian workers, such as technical representatives aboard a warship or employees in a munitions factory, in or on a military objective, does not alter the status of the military objective. These civilians may be excluded from the proportionality analysis.
Civilians who voluntarily place themselves in or on a military objective as “human shields” in order to deter a lawful attack do not alter the status of the military objective. While the law of armed conflict is not fully developed in such cases, such persons may also be considered to be taking a direct part in hostilities or contributing directly to the enemy’s warfighting/war-sustaining capability, and may be excluded from the proportionality analysis. Attacks under such circumstances likely raise political, strategic, and operational issues that commanders should identify and consider when making targeting decisions. 
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 1989, a US memorandum of law concerning the prohibition of assassination stated:
Civilians who work within a military objective are at risk from attack during the times in which they are present within that objective, whether their injury or death is incidental to the attack of that military objective or results from their direct attack … The substitution of a civilian in a position or billet that normally would be occupied by a member of the military will not make that position immune from attack. 
United States, Department of the Army, Office of the Judge Advocate General, Memorandum of Law: Executive Order 12333 and Assassination, 2 November 1989, The Army Lawyer, Pamphlet 27-50-204, December 1989.
In 1992, in its final report to Congress on the conduct of the Gulf War, the US Department of Defense stated:
Civilians using those bridges or near other targets at the time of their attack were at risk of injury incidental to the legitimate attack of those targets … The presence of civilians will not render a target immune from attack; legitimate targets may be attacked wherever located (outside neutral territory and waters). 
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. 624 and 625.