A/HRC/42/CRP.1 910. A particular problem that arises in conflict situations is that, generally, virtually all the relevant information remains in the hands of one party. It is this particular factor that may require more transparency in the type of investigation that needs to be conducted. 1441 911. Other proactive steps to bring to an end violations by parties to the conflict must be carried out with due diligence.1442 Third States are free to choose between different possible measures, as long as they are designed to ensure respect for the law. This implies, for example, that the continued adoption of a measure that has so far proven to be ineffective to ensure respect of the law may no longer be considered as adequate. Engaging in diplomatic dialogue, lending good offices, offering legal assistance and referrals to international bodies are examples of measures. However, the measures can also be stronger and include measures of retorsion, such as trade restrictions and the suspension of aid or cooperation agreements.1443 912. The measures that third States are expected to take differ according to the level of influence that a State exercises on the party to the conflict. 1444 In Yemen, the responsibility to take measures increases with the level of influence that a specific State has over the Government of Yemen, members of the coalition or the Houthis. This is particularly pertinent for States – in addition to members of the coalition that are directly involved as parties to the conflict – that provide support, directly or indirectly, to a party to the conflict through expert advice, intelligence, training, logistic support and/or the transfer of weapons. As regards the situation in Yemen, third State responsibility is thus particularly relevant, amongst others, for the United States, 1445 the United Kingdom,1446 France,1447 and the Islamic Republic of Iran,1448 in view of the influence that these States exert on parties to the conflict. 913. The issue of arms transfer is illustrative insofar as it implies obligations to take both negative and positive measures. On the one hand, the obligation to ensure respect requires that States refrain from transferring weapons “if there is an expectation, based on facts or For the consequences of this under human rights law, see Mansuroğlu v. Turquie, 43443/98, European Court of Human Rights, judgment of 26 February 2008. 1442 The obligation entailed in Art. 1 common to the Geneva Conventions can be seen as an obligation of due diligence, in opposition to an obligation of result (see Knut Doermann and Jose Serralvo, “Common Article 1 to the Geneva Conventions and the obligation to prevent international humanitarian law violations”, International Review of the Red Cross (2014), 96 (895/896), p. 710 (https://www.icrc.org/en/international-review/article/common-article-1). 1443 ICRC commentary to article 1 common to the Geneva Conventions, 2016, para. 181; see for example Updated European Union Guidelines on promoting compliance with international humanitarian law, 2009/C 303/06 (https://eur-lex.europa.eu/legalcontent/EN/TXT/?uri=celex:52009XG1215(01), which provides examples of means at the disposal of the EU in its relation with third countries. 1444 See ICRC Customary IHL study, rule 144 and ICRC commentary to article 1 common to the Geneva Conventions, 2016, para. 165. 1445 For the United States involvement in the conflict in Yemen, see for example: Larry Lewis, “Promoting Civilian Protection during Security Assistance: Learning from Yemen”, CNA Analysis and Solutions, May 2019, p. 9 (https://www.cna.org/CNA_files/PDF/IRM-2019-U-019749Final.pdf). 1446 For the United Kingdom’s involvement in the conflict in Yemen, see for example: “Britain’s Hidden War”, Channel 4 Dispatches, April 2019 (https://www.channel4.com/press/news/britainshidden-war-channel-4-dispatches). 1447 For France’s involvement in the conflict in Yemen, see for example: Discolose, “La France et le Yémen: cartographie d’un mensonge d’Etat”, Mediapart, April 2019 (https://www.mediapart.fr/journal/international/150419/la-france-et-le-yemen-cartographie-d-unmensonge-detat?utm_content=buffer5e34b&utm_medium=social&utm_source=Facebook_Page&utm_campaign =CM). According to the findings of the Panel of Experts appointed to monitor compliance with the sanctions set up by Security Council resolution 2216(2015), Iran had failed to take the necessary measures to prevent the transfer of weapons to the Houthis (United Nations Security Council - Letter dated 26 January 2018 from the Panel of Experts on Yemen mandated by Security Council resolution 2342 (2017) addressed to the President of the Security Council (S/2018/68), para. 13). 1441 218