القاعدة ذات الصلة
Switzerland
Practice Relating to Rule 20. Advance Warning
Switzerland’s Basic Military Manual (1987) states: “During every attack, commanding officers at the battalion or group level, and those of higher ranks, shall take care that the civilian population is warned if possible.” 
Switzerland, Lois et coutumes de la guerre (Extrait et commentaire), Règlement 51.7/II f, Armée Suisse, 1987, Article 29(1).
Switzerland’s Regulation on Legal Bases for Conduct during an Engagement (2005) states:
165 The following precautionary measures must be taken into consideration when making decisions, when issuing orders and in particular when conducting military operations.
168 If military circumstances permit, effective advance warning must be given of attacks which may affect the civilian population. 
Switzerland, Bases légales du comportement à l’engagement (BCE), Règlement 51.007/IVf, Swiss Army, issued based on Article 10 of the Ordinance on the Organization of the Federal Department for Defence, Civil Protection and Sports of 7 March 2003, entry into force on 1 July 2005, §§ 165 and 168.
In 2005, Switzerland withdrew its reservations to Articles 57 and 58 of the 1977 Additional Protocol I. 
Switzerland, Withdrawal of reservations to the 1977 Additional Protocol I, 17 June 2005.
In 2010, in its Report on IHL and Current Armed Conflicts, Switzerland’s Federal Council stated:
Military responses to guerrilla tactics must be in conformity with the requirements of international humanitarian law. There is a consensus today that the majority of the provisions of [the 1977] Additional Protocol I apply equally to non-international conflicts through customary law. … Even if combatants blend in with the civilian population and use it as a human shield in violation of the law, it is necessary … to spare civilians as much as possible (for example by warning them in advance). 
Switzerland, Federal Council, Report on IHL and Current Armed Conflicts, 17 September 2010, Section 3.4, p. 13.
[footnotes in original omitted]