3.The State planning the meaoures shall, at the request of the other States, promptly enter into consultations and negotiations with them in the manner indicated in paragraphs 1 and 2 of article 17. Nothing contained in articles 10 to 19 shall oblige a watercourse State to provide data or information vital to its national defence or security. Nevertheless, that State shall co-operate in good faith with the other watercourse States with a view to providing as much information ‘ as possible under the circumstances. indirect. In cases where there are serious obstacles to direct contacts between watercourse States, the States concerned shall proceed to any exchsnga of data and information, notification, communication, consultations and negotiations provided for in articles 10 to 20 through any indirect procedure accepted by them. l3i.91 This article is based on article 15 as proposed by the Special Rapporteur in 1987. uQ/ This article is based on article 15 [16] as proposed by the Special Rapporteur in 1988. - 144 -PART IV PROTECTION AND PRESERVATION Watercourse States shall, individually or jointly, protect and preserve the ecos;qtems of international watercourse[s] [eystams]. 1. For the purposes of the present draft articles, “pollution of an international watercourse [system]” means any detrimental alteration in the composition or quality of the waters of an international watercourse [system] which results directly or indirectly from human conduct. 41 2. Watercourse States shall, individually or jointly, prevent, reduce and control pollution of an international watercourse [eystam] that may cause appreciable harm to other watercourse States or to their environment, including harm to human health or safety, to the use of the waters for any beneficial purpose or to the living resources of the international watercourse [system]. Watercourse States shall take steps to harmonise their policies in this connection.
**Analysis**
The text appears to be related to the management and protection of international watercourses, which is a crucial aspect of environmental protection and sustainable development. The articles discuss the need for cooperation and information sharing among watercourse states to prevent and control pollution, which has implications for human health, safety, and the environment.

**Category**
Natural resources and environment, International relations