援军，增援部队
soldiers sent to join an army to make it stronger
Massive troop reinforcements were sent into the region.
A thousand more soldiers are being sent as reinforcements.
Reserve troops were called in as reinforcements on the front line.
They sent 25 platoons and two air-support units in as reinforcements.
The paratroopers who had arrived as reinforcements were now under siege inside the compound.
Military trucks had brought in reinforcements earlier in the day, but came under heavy fire leaving the base.
See also: reinforcement