Tarkov Lore
USEC
TerraGroup's private army, stranded with everyone else
United Security, USEC, was founded in 1999 through the merger of two private security firms. It grew into a global private military company with a staff of over seven and a half thousand, and in 2004 it found the client that would define it: the TerraGroup international holding.
USEC became, in practice, TerraGroup's private army. Its mandate in Tarkov was to destroy evidence of the company's illegitimate research and keep the facilities out of the hands of BEAR, the PMC hired by the Russian government to investigate. USEC and BEAR clashed wherever TerraGroup operated, from Norvinsk to postings abroad.
When the Contract Wars ignited and the blockade sealed the region, USEC operatives were abandoned along with everyone else. The rogue ex-USEC squads on Lighthouse, and the Goons themselves, are what happens to a private army when the contracts stop mattering.
As a playable faction, USEC characters speak English and carry western-flavored gear and voice lines. Mechanically the choice is mostly identity, with a few wrinkles like Lighthouse Rogues holding their fire on USEC players unless provoked.