Related Rule
Netherlands
Practice Relating to Rule 144. Ensuring Respect for International Humanitarian Law Erga Omnes
The Military Manual (2005) of the Netherlands states:
Section 5 - Protecting powers and organizations of the Red Cross
0238. Protecting powers
The parties to a conflict are bound, from the beginning of that conflict, to ensure observation and implementation of the rules of the humanitarian law of war. They must do this through the system of protecting powers. A protecting power is a neutral or other State, not involved in the conflict, which ensures that the rights and interests of a belligerent and, above all, those of the civilians and military of that State are assured and protected.
0240. The International Committee of the Red Cross (ICRC)
If the parties in a conflict cannot agree to accept the protecting powers appointed by the other party, the ICRC may offer to act as a substitute for a protecting power. The ICRC can function as a protecting power only after the affected parties in the conflict have given their consent. 
Netherlands, Humanitair Oorlogsrecht: Handleiding, Voorschift No. 27-412, Koninklijke Landmacht, Militair Juridische Dienst, 2005, §§ 0238 and 0240.
In its chapter on the prevention and punishment of war crimes, the manual states:
Section 3 - Compliance
1108. Breaches of the humanitarian law of war have occurred in every armed conflict. Yet ICRC data show that, in many cases, the rules of the humanitarian law of war prevent or mitigate suffering. The following factors are important to compliance with the humanitarian law of war:
1115. Diplomatic pressure
Diplomatic pressure can be very important to compliance with the rules of international law, and therefore also with those of the humanitarian law of war. The intervention of other States, international organizations, also church and humanitarian organizations, may have a positive influence on compliance with the rules.
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1117. Protecting powers
A protecting power is a State which is not a party to the conflict. It is appointed by a party to the conflict, and accepted by the other party, to fulfil the tasks set forth in the Geneva Conventions and AP I [1977 Additional Protocol I]. A protecting power is primarily responsible for safeguarding the interests of a party to the conflict.
1119. International Fact-Finding Commission
Since 1990, an International Fact-Finding Commission has been established, consisting of fifteen impartial members. The Commission is authorized to investigate in parties to a conflict that have recognized the Commission, any fact allegedly forming a serious infringement of the humanitarian law of war. The Commission is also authorized to provide its good offices to promote respect for the rules of the humanitarian law of war. 
Netherlands, Humanitair Oorlogsrecht: Handleiding, Voorschift No. 27-412, Koninklijke Landmacht, Militair Juridische Dienst, 2005, §§ 1108, 1115, 1117 and 1119.