Sentry drone

Sentry drones were American remote-controlled automated vehicles with scanning equipment, deployed during the GLA Conflict.
==Background==
Sentry Drones were purely autonomous robots deployed by the forces of the United States and its branches. As their name suggested, these robots were primarily used to monitor base perimeters. By default, they exposed invisible enemies for nearby allies to eliminate, though they could also be upgraded with a 20mm machine gun to allow them to engage to opponents by themselves. When idle they were completely invisible, which allowed them to surprise and eliminate opposing scouts.
While their invisibility certainly suited defensive watch duties, the United States were also known to deploy these drones as heavier support in covert operations. Their 20mm guns were effective at cutting through both infantry and light vehicles, which made them a valuable multipurpose asset for operations in too deep for heavier reinforcements.
China's General Leang appeared to also utilize Sentry Drones on the rare occasions her forces were sighted on the battlefield. How she managed this feat is still unknown, however, since these were developed and deployed otherwise exclusively by the United States.
==Game unit==
Sentry Drones are reasonably cheap scouts whose main traits are their considerable speed, inherent stealth, and their stealth detection ability. 
Their availability, stealth, and stealth detection allows them to observe large portions of the battlefield, monitor nearby troop movements and expose nearby invisible operatives. Their lower cost also meant that the exposure and destruction of a Sentry Drone was not a significant loss. Each Drone's speed also gave them great flexibility and allowed them to rapidly secure and stand sentinel over important battlefield positions, and their small size also meant that in heavier transports they occupied roughly only the space an infantryman took up. Unfortunately, they were not quite small enough to fit in most infantry-minded transports, such as the American Humvee. 
Sentry Drones gained greater utility once upgraded with a Sentry Drone Gun which, combined with their camouflage and stealth detection, makes them ideal at ambushing weaker enemies. They could take and hold portions of the battlefield to a limited degree. A strategically placed team of Sentry Drones can ambush and obliterate a group of unsuspecting artillery units before any displaced guard forces can return. 
Their ability to sit in locations without being noticed also made them ideal at infiltrating enemy lines and ripping apart thinly armored Chinese and GLA resource gatherers, but not USA Chinooks, as it cannot target aircraft.
Since they are also remotely-controlled, unmanned machines, they are immune to the attacks of Jarmen Kell, Hijackers, Nuke Cannon's Neutron Shells and Neutron Mines. Once armed, they are particularly good counter-sniper units, as they can detect both Jarmen Kell and Pathfinders, running them down and eliminating them fairly rapidly.
Due to their deployment of a wide variety of drones, American engineers also designed additional armor that could be applied to their drones to increase their resilience to enemy fire. 
===Counters===
However, Sentry Drones were quite fragile vehicles. Their main method of self-defense, aside from their upgradable gun, was to avoid being seen at all; once exposed, they could not take much of a beating before being put out of commission. They would become visible upon firing. Even with a gun, Sentry Drones lacked effectiveness against medium or heavy armor and were unable to fire at aircraft.
Their mechanical nature also meant that they were unable to gain battlefield experience, and therefore could not be fixed with superior weaponry, better armor, or self-repair modules like more conventionally crewed vehicles could be, although these are generally not problematic given they're primarily used to provide recon. The small profile of the Drone, while affording great speed, also meant that they could not crush infantry and had to either run away or hide from what they could not deal with.
The largest drawback was that it suffered from a slight delay when executing orders. This long-than-deal reaction time makes them inferior to Humvees as scout vehicles.
===Upgrades===
==Changelog==
* Zero Hour patch 1.03: 
** no longer automatically engages on enemy units when stealthed
** now benefits from drone armour upgrade
==Trivia==
* The sentry drone appears to be a larger version of the TALON robot presently used by the US military.
** The larger size appears to be needed to accommodate the 20mm auto cannon that can be installed on it.
* The Sentry Drone's delayed response to commands uses the Nuclear Cannon's/Listening Outpost's unpack/repack function to hold the Drone back for a few seconds when given a move order.
** Thus, it responds to attack orders (within its current range) immediately.
==See Also==
* Robotics, similar American drone technology
* Listening Outpost/Attack Outpost
Category:Zero Hour vehicles
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ru:Зонд "Часовой"