Artikel 21

1. Where an investigation is initiated or an arrest made by a German authority in respect of an act punishable under Article 7 of the Fourth Law Amending the Criminal Law dated 11 June 1957 (Bundesgesetzblatt Teil I, page 597) or under such legislation as may replace that Article in future, the German authorities conducting the investigations shall notify the military authorities of the sending State concerned without delay. The same shall apply if a German authority initiates an investigation or makes an arrest in respect of an act otherwise directed against the security of a sending State or of its force.
2. Where an investigation is initiated or an arrest made in the Federal territory by a competent authority of a sending State in respect of an act committed in the Federal territory and relating to matters affecting the security of the Federal Republic, this authority shall inform the German authorities without delay.