Related Rule
Netherlands
Practice Relating to Rule 43. Application of General Principles on the Conduct of Hostilities to the Natural Environment
The Military Manual (2005) of the Netherlands states: “It is also forbidden to use methods or means which cause extensive, long-lasting and serious damage to the natural environment, or which may be expected to cause such damage.” 
Netherlands, Humanitair Oorlogsrecht: Handleiding, Voorschift No. 27-412, Koninklijke Landmacht, Militair Juridische Dienst, 2005, § 0404; see also § 0405.
In its chapter on non-international armed conflict, the manual states:
The natural environment
Areas (of land or sea) may be attacked only if they are a military objective and may be occupied or used for military purposes only if a military need for this exists. Where this occurs, or other military objectives are attacked, damage to the natural environment must be limited. 
Netherlands, Humanitair Oorlogsrecht: Handleiding, Voorschift No. 27-412, Koninklijke Landmacht, Militair Juridische Dienst, 2005, § 1037.
Under the International Crimes Act (2003) of the Netherlands, “intentionally launching an attack in the knowledge that such an attack will cause … widespread, long-term and severe damage to the natural environment which would be clearly excessive in relation to the concrete and direct overall military advantage anticipated” is a crime, when committed in an international armed conflict. 
Netherlands, International Crimes Act, 2003, Article 5(5)(b).