uncharted territory

незвідана територія; незнайома область; щось зовсім нове (терра інкогніта) (With Pentagon purge, Trump thrusts military into uncharted territory, - The Washington Post, 23 February 2025)

uncharted waters

sail in uncharted waters

acquisition of land / territory

enemy-held territory

hostile territory

incursion into enemy territory

state territory

swift entry into hostile territory

territory transfer

insert special forces teams into enemy territory

aerodrome adjacent territory

densely populated (densely-populated) area (region) / territory / country

absorption of territory

armor territory (terrain)

Russian-held territory

take back territory