The secret base of the NSA (aka Secret Base) is an Echelon spies vs. UPSILON Force bonus multiplayer map, and it is downloadable for the Xbox 360 and PS3. According to the Tom Clancy's Splinter Cell: Double Agent website, the level is based in a secret base belonging to the National Security Agency. It is guarded by UPSILON Mercenaries (an organization with apparent connections to the Pentagon who defend it against intruding Echelon spies.
The secret base is a particurarly large (and futuristic) structure made out of metal and glass. Its location unknown but seems to be near water (as sea gulls and buoys can be heard). It has a helicopter launchpad off to one side.
The mission objective of the Echelon spies is to infiltrate the heavily guarded building, hack highly protected servers, and extract - securing the data back at their base. They must avoid the Upsilon Mercenaries guarding the installation.
- Goal: Echelon spies must reach the mission objectives, hack them, and bring two complete files to the control drone.
- Victory: Two files secured or all Mercenaries eliminated within the time limit.
- Infiltration: Reach the objectives, hack them, and complete one file.
- Exfiltration: Bring the complete file back to your control drone.
- File Secure: The aim of the Echelon spies is to download and secure two confidential files. Each terminal can only give 25% of the Information (2 lives per spy / 10 minutes per game).
- Download as you can: Echelon spies secure as many complete files as possible within a limited timeframe (2 lives per spy / 12 minutes per game).
Upsilon Mercenaries objective is to defend the data nodes in the base from the invading spies. The mercenaries must spot intruders, track down and eliminate them, and keep their systems secure.
- Goal: Protect the mission objectives and eradicate any intruders.
- Victory: All spies killed or time limit reached before two files are secured by the Spies.
- Infiltration: Protect the objectives by preventing the Spy team from hacking them. Track the enemies and kill them.
- Exfiltration: Retrieve the stolen file by eliminating the intruder before he reaches the drop zone (control drone).
- Upsilon's connection to the Pentagon (the Department of Defense) could explain why Upsilon would be trying to defend an NSA building from the intruding spies of Echelon.