17 and include the management of stress in use-of-force situations. Training should be institutionalized by law enforcement agencies and, where external assistance is offered, it should not be provided solely by the manufacturer of a particular weapon. Training programmes should be reviewed continuously, to incorporate lessons learned during operations and to ensure that they reflect all relevant policies and updated internal regulations.54 Moreover, States should consider inviting technical support from relevant international organizations and law enforcement agencies from other countries. 4.5.2 Law enforcement officials shall receive appropriate initial and refresher training in the use and effects of any less-lethal weapons with which they have been equipped or deployed. The training should be to a high standard, and trainees should be authorized to carry and use only those weapons in which they have been trained successfully. Command and supervisory officials should also receive ongoing training on their obligations, arising from their command functions, in areas relating to the use of force.55 4.5.3 Training should include information on the particular vulnerabilities of certain individuals to the effects of a particular weapon, and on how to identify especially vulnerable individuals.56 Trainees shall be made aware not only of the primary risk of injury arising from use of any less-lethal weapons with which they may be equipped but also of the secondary injuries that may result (for example, if a person against whom the weapon is used falls from an elevated position or onto a hard surface). These effects and risks should also be reflected in standard operating procedures. 4.5.4 In accordance with the human rights principle of precaution, appropriate emergency first-aid training shall be provided for all law enforcement officials to enable them to respond effectively to the injuries or other impact that may result from the use of the weapons with which they are equipped. OHCHR, Human Rights and Law Enforcement: A Manual on Human Rights Training for Law Enforcement Officials, chap. 5; and OSCE/ODIHR and Council of Europe, Guidelines on Freedom of Peaceful Assembly, para. 178. 55 OHCHR, Human Rights and Law Enforcement: A Manual on Human Rights Training for Law Enforcement Officials, chap. 5. 56 Basic Principles, principles 19 and 20. See also the report of the Special Rapporteur on extrajudicial, summary or arbitrary executions (A/HRC/26/36), para. 106. 54