As much as practicable, officers should follow the proactive procedures above-and have an executed Warrant of Apprehension and Removal-before contacting an Alien Enemy. However, that will not always be realistic or effective in swiftly identifying and removing Alien Enemies. For example, consistent with the law, officers may need to contact a suspected Alien Enemy to develop further facts or otherwise confirm any of the four requirements for validation as an Alien Enemy. Or an officer may encounter a suspected Alien Enemy in the natural course of the officer's enforcement activity, such as when apprehending other validated members of Tren de Aragua. Given the dynamic nature of enforcement operations, officers in the field are authorized to apprehend aliens upon a reasonable belief that the alien meets all four requirements to be validated as an Alien Enemy. This authority includes entering an Alien Enemy's residence to make an AEA apprehension where circumstances render it impracticable to first obtain a signed Notice and Warrant of Apprehension and Removal (Form AEA-21B).