surveillance, under surveillance

surveillance, high- and low-altitude surveillance

foot march under packs

hand-held under-barrel grenade launcher

restricted area (under military jurisdiction)

under armor auxiliary power unit (UAAPU)

under arms

under barrel grenade launcher (UBGL)

under canvas

under command of

under cover of

under fire

under hatches

Under Secretary of Defense (USD)

Under Secretary of Defense for Acquisition, Technology, and Logistics (USD AT&L)

Under Secretary of Defense for Intelligence USD(I)

under-strength unit

under-vehicle improvised explosive device (UVIED)

nap-of-the-earth (NOE) (ground-hugging / terrain masking / flying under the radar / hedgehopping)

UBACS / Under Body Armour Combat Shirt

under nonnuclear conditions

under nuclear conditions

assume obligations under a treaty

office of the under secretary of defense for acquisition and technology

be active under the cover of civil society organisations

be under cover

under cover of civilian research

under cover of the Consulate General

under cultivation

under deep cover

under hood

under suspicion of posing a threat to democracy

under zero angle of incidence