Related Rule
United States of America
Practice Relating to Rule 54. Attacks against Objects Indispensable to the Survival of the Civilian Population
The US Naval Handbook (1995) prohibits the “intentional destruction of food, crops, livestock, drinking water and other objects indispensable to the survival of the civilian population, for the specific purpose of denying the civilian population of their use”. 
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), § 8.1.2.
The Annotated Supplement to the US Naval Handbook (1997) provides that the rule prohibiting the intentional destruction of objects indispensable to the survival of the civilian population for the specific purpose of denying the civilian population of their use is a “customary rule … accepted by the United States … and is codified in [the 1977 Additional Protocol I], art. 54(2)”. 
United States, Annotated Supplement to the Commander’s Handbook on the Law of Naval Operations, prepared by the Oceans Law and Policy Department, Center for Naval Warfare Studies, Naval War College, Newport, Rhode Island, November 1997, § 8.1.2, footnote 15.
The US Naval Handbook (2007) states: “The intentional destruction of food, crops, livestock, drinking water, and other objects indispensable to the survival of the civilian population, for the specific purpose of denying the civilian population of their use, is prohibited.” 
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.
In 2008, in the Agent Orange case, the US Court of Appeals for the Second Circuit upheld the dismissal of the case by the District Court, finding that the Plaintiffs had failed to demonstrate a violation of international law. In its judgment, the Court of Appeals stated:
The sources of international law relied on by Plaintiffs do not support a universally-accepted norm prohibiting the wartime use of Agent Orange that is defined with the degree of specificity required by Sosa Sosa v. Alvarez-Machain, 542 U.S. 692 (2004)]. Although the herbicide campaign may have been controversial, the record before us supports the conclusion that Agent Orange was used as a defoliant and not as a poison designed for or targeting human populations. Inasmuch as Agent Orange was intended for defoliation and for destruction of crops only, its use did not violate the international norms relied upon here, since those norms would not necessarily prohibit the deployment of materials that are only secondarily, and not intentionally, harmful to humans. 
United States, US Court of Appeals for the Second Circuit, Agent Orange case, Judgment, 22 February 2008, pp. 26 and 27.
During the Korean War, the Commanding General of the US Far East Air Force refused to bomb dams in North Korea since he was “concerned over the political impact of destroying food crops” which would have resulted from such attacks. 
Robert F. Futrell, The United States Air Force in Korea 1950-1953, Office of Air Force History, US Air Force, Washington, D.C., Revised edition, 1983, p. 667.
In 1973, a Deputy Legal Adviser of the US Department of State declared: “The generally accepted rule today is that crops and food supplies may be destroyed if they are intended solely for the use of armed forces.” 
United States, Address by George H. Aldrich, Deputy Legal Adviser of the Department of State, 13 April 1973, reprinted in Arthur W. Rovine, Digest of United States Practice in International Law, 1973, Department of State Publication 8756, Washington, D.C., 1974, pp. 503–504.
In its reservation made upon ratification of the 1996 Amended Protocol II to the Convention on Certain Conventional Weapons, the United States stated:
The United States reserves the right to use other devices … to destroy any stock of food or drink that is judged likely to be used by an enemy military force, if due precautions are taken for the safety of the civilian population. 
United States, Reservation made upon acceptance of Amended Protocol II to the Convention on Certain Conventional Weapons, 24 May 1999, § I.
According to the Report on US Practice, it is the opinio juris of the United States that foodstuffs and crops may be destroyed if it can be determined that they are destined for enemy armed forces. 
Report on US Practice, 1997, Chapter 4.1.
In 2005, the US Department of Justice submitted a Statement of Interest of the United States to the US District Court for the Eastern District of New York prior to that Court’s consideration of Agent Orange Product Liability Litigation (The Vietnam Association for Victims of Agent Orange/Dioxin, et al. v. Dow Chemical Company, et al). The statement reiterated the US position that no rule of international law barred the use of chemical herbicides in war generally nor barred the destruction of crops intended for use by enemy forces. With regard to crop destruction operations, it stated:
The United States Consistently Has Taken the Position that No Rule of International Law Barred the Crop Destruction Operations Undertaken in Vietnam
Similarly, the United States had long interpreted 1907 Hague Convention Respecting the Laws and Customs of War on Land (“1907 Hague Convention” or “Convention”), 36 Stat. 2277 (1910), international law generally, as not prohibiting the destruction of crops intended for use by enemy forces, precisely the type of crop destruction operations undertaken in Vietnam.
A. The Executive Branch Consistently Has Taken the Position that No Rule of International Law Bars the Destruction of Crops Intended for Use By Enemy Forces
As noted above, in 1945 the Judge Advocate General of the War Department provided an opinion as to the legality, under international law, of “certain crop-destroying chemicals which can be sprayed by airplane against enemy cultivations.” Cramer Opinion.
The Cramer Opinion concluded that “the use of chemical agents to destroy cultivations or retard their growth, would not violate any rule of international law prohibiting poison gas.” Cramer Op.
3. The Opinion also addressed other possible international law prohibitions on the destruction of enemy crops, including the 1907 Hague Convention:
Nor does the prohibition against using “poison or poisoned weapons” in Article 23 a of the Regulations annexed to the Hague Convention (IV) of 1907 render the use of these chemicals illegal. Even if Article 23 a is held to apply to toxic chemical substances, it would not preclude the use of crop-destroying chemicals which produce no noxious effect upon enemy soldiers
The proposed target of destruction, enemy crop cultivations, is a legitimate, one, inasmuch as a belligerent is entitled to deprive the enemy of food and water, and to destroy his sources of supply whether in depots, in transit on land, or growing in his fields.
This same conclusion was reached by the General Counsel of the Department of Defense a quarter-century later:
[N]either the Hague Regulations nor the rules of customary international law applicable to the conduct of war and to the weapons of war prohibit the use of antiplant chemicals for destruction of crops, provided that their use against crops does not cause such crops as food to be poisoned nor cause human beings to be poisoned by direct contact, and such use must not cause unnecessary destruction of enemy property
[T]he use of chemical herbicides is not prohibited by article 23(a) or any other rule of international law. It involves an attack by unprohibited means against legitimate military objectives. But an attack by any means against crops intended solely for consumption by noncombatants not contributing to the enemy’s war effort would be unlawful for such would not be an attack upon a legitimate military objective. Where it cannot be determined whether the crops were intended solely for consumption by the enemy’s armed forces, crop destruction would be lawful if a reasonable inquiry indicated that the intended destruction is justified by military necessity under the principles of Hague Regulation Article 23(g), and that the devastation occasioned is not disproportionate to the military advantage gained.
Buzhardt Letter, reprinted at 1971 Senate Hearings at 315–17.
The Army Field Manual took the same position, stating that Article 23(a) “does not prohibit measures taken to destroy, through chemical … agents harmless to man, crops intended solely for consumption by the armed forces (if that fact can be determined).” Department of Army Field Manual, FM 27-10, The Law of Land Warfare (July 1956), ¶ 37, reprinted in Buzhardt Letter. See also 1971 Senate Hearings at 315 (discussing Field Manual); 1969 House Hearings at 215 (same).
B. The United States Crop Destruction Operations in Vietnam Focused on Crops Intended for Enemy Forces
The United States’ use of chemical herbicides in Vietnam carefully hewed to this longstanding interpretation of international law. The initial use of chemical herbicides in Vietnam was restricted to defoliation operations. Am. Compl., ¶ 54-55; William A. Buckingham, Jr., Operation Ranch Hand: The Air Force and Herbicides in Southeast Asia 1961-1971 (Office of Air Force History 1982) (“Operation Ranch Hand”) at 21
After those initial defoliation operations, in 1962 President Kennedy decided to allow restricted crop destruction to proceed. Id. at 78; Am. Compl., ¶ 55. The President’s decision was accompanied by instructions that “the targets should be chosen so as to cause the least damage possible to non-Viet Cong farmers,” Buckingham, Operation Ranch Hand at 79.
The crop destruction program was thus focused on “crops intended for the use of Vietcong or North Vietnamese forces” in Vietcong-held territory. 1969 House Hearings at 215 (Testimony of Mr. Pickering). See also id. at 197 (crop destruction undertaken only after “very thorough review” and “very thorough conclusions” about crops before destruction operations) (Testimony of Mr. Pickering), 229 (“friendly crops” excluded from target areas and all crop destruction projects approved by Ambassador) (Statement of Adm. Lemos); Buckingham, Operation Ranch Hand at 83. Thus, in a message from the State Department regarding the use of herbicides in crop destruction, the following guideline was issued by Secretary of State Rusk:
Crop Destruction: 1. All crop destruction operations must be approved in advance by Assistant Secretary FE [Far East] and DOD. Guidelines re Crop Destruction: a) crop destruction must be confined to remote areas known to be occupied by VC. It should not be carried on in areas where VC are intermingled with native inhabitants and latter cannot escape.
Deptel #1055 SECSTATE to AMEMBASSY Saigon, May 7, 1963, quoted in Buckingham, Operation Ranch Hand at 86.
This same policy of focusing crop destruction on enemy crops continued throughout the war. As explained by Rear Admiral Lemos in 1969:
[W]e are really talking about very isolated crops in areas of known Vietcong and North Vietnamese army units, and which are clearly a part of that complex and being used, or being grown by them, or by people forced by them to grow for them.
1969 House Hearings at 250 (Testimony of Adm. Lemos). See also id. at 251 (“crop destruction program is associated with enemy camp areas and not the villages and hamlets”). Thus, before crop destruction could be approved, there “ha[d] to be substantial evidence that the crops are being grown specifically for the use of Vietcong troops and North Vietnamese troops.” Id See also 1971 Senate Hearings at 315 (Testimony of Mr. Nutter). As a result, the crop destruction program was only a small part of the overall use of herbicides in Vietnam. 1969 House Hearings at 250.
In early December 1970, the decision was made to completely phase out the crop destruction program. Buckingham, Operation Ranch Hand at 172; 1971 Senate Hearings at 3 (“immediate termination of all use of chemical herbicides in Vietnam for crop destruction purposes”) (Statement of Secretary of State Rogers), On January 16, 1971, the Deputy Secretary of Defense ordered the immediate termination of all crop destruction operations by U.S. forces. Buckingham, Operation Ranch Hand at 175.
No Universally Adopted and Specifically Defined Norm Prohibited the Destruction of Enemy Crops
For similar reasons, to the extent that Plaintiffs’ claims are based on the use of chemical herbicides to destroy crops intended for use by enemy forces, they too fail to meet the exacting standards required by Sosa [Sosa v. Alvarez-Machain, US Supreme Court, 2004]. For, as discussed above, the United States consistently has taken the position that neither the 1907 Hague Convention nor any other rule of international law prohibited the enemy crop destruction operations undertaken in Vietnam. Any norm of international law that may have existed with respect to crop destruction prohibited solely the destruction of crops intended for non-combatants. Particularly given the United States’ longstanding position that neither conventional nor customary international law prohibited the use of herbicides to destroy enemy crops, no international norm prohibiting such practices was widely accepted by “civilized nations.” For the same reasons discussed above with respect to the use of herbicides generally, therefore, no federal common law cause of action should be recognized based on the use of herbicides for crop destruction purposes. 
United States, Department of Justice, Statement of Interest of the United States submitted to the US District Court for the Eastern District of New York, In re: Agent Orange Product Liability Litigation (The Vietnam Association for Victims of Agent Orange/Dioxin, et al. v. Dow Chemical Company, et al), 12 January 2005,§ II, pp. 9–13 and 32–33.
In 1973, a Deputy Legal Adviser of the US Department of State declared: “The generally accepted rule today is that crops and food supplies may be destroyed … if their destruction is required by military necessity and is not disproportionate to the military advantage gained.” 
United States, Address by George H. Aldrich, Deputy Legal Adviser of the Department of State, 13 April 1973, reprinted in Arthur W. Rovine, Digest of United States Practice in International Law, 1973, Department of State Publication 8756, Washington, D.C., 1974, pp. 503–504.
According to the Report on US Practice, the opinio juris of the United States recognizes the legality of attacks against objects indispensable to the survival of the civilian population when required by military necessity. 
Report on US Practice, 1997, Chapter 4.1.