Explosive (the 'E' in CBRNE) attacks in modern terrorism most commonly involve:

Explanation

Improvised Explosive Devices are by far the most common explosive threat — homemade devices using readily available materials, often hidden in vehicles (VBIEDs), worn by attackers (PBIEDs), placed in packages, or mailed. Standoff distances and pre-event SAR observation (probing security, surveillance, acquiring precursors) are the principal defenses. Military munitions (a) are tightly controlled; nuclear devices (b) are extremely rare; firearms (d) are a different attack mode altogether. Security officers focus on access control, suspicious-package awareness, and reporting indicators of pre-attack preparation.