There’s no single, objective answer — “most lethal” depends on mission, metrics (training, experience, equipment, intel support) and rules of engagement. Commonly cited contenders are:
- USA (JSOC units like Delta Force and DEVGRU) — huge resources and global combat experience.
- UK SAS/SBS — long history in direct action and counterterrorism.
- Israel’s Sayeret Matkal — elite counterterror/hostage‑rescue record.
- Russian Spetsnaz, French GIGN/Commandos, Australian SASR and others — all elite in different roles.
Which role (counterterror, reconnaissance, hostage rescue, unconventional warfare) do you mean?