SDI Defense (Civ2)

SDI Defense
Advance required	Laser
Buildings required	None
Cost	200
Maintenance	4
Effect	Protects everything within three spaces of the city from nuclear attack.

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The SDI Defense is a defensive city improvement in Civilization II, available with The Laser advance. It protects everything within a three-tile radius of its host city against nuclear weapons, and doubles garrisoned units' defense against conventional missiles.

Strategy

The SDI Defense is the only countermeasure against a nuclear attack. Foreign missiles that attempt to attack targets within the SDI's range are immediately intercepted and destroyed, with both players notified by an advisory popup. SDI will not intercept a player's own missiles, nor does it prevent blast damage from attacks against the fourth tile outside its perimeter.

SDI is a priority for the player's most populous and prosperous cities: each nuclear strike halves citizen count, so built-up metropoli suffer greater devastation than small towns. Total destruction of the garrison also leaves a city vulnerable to capture by Paratroopers, a common tactic by computer opponents. Due to SDI's high  Production cost, it may be necessary to buy the improvement outright to protect newly-captured cities from retaliatory strikes: the AI does not discriminate between foreign cities and its former possessions.

SDI doubles the city garrison's defense against Cruise Missiles. This bonus compounds with the SAM Missile Battery: a city with both SAM and SDI gains a fourfold defense.

SDI cannot be targeted for sabotage by espionage units. Cities with SDI remain vulnerable to "suitcase nukes", however these pose the risk of triggering global condemnation even if the player is at war with the target.

Civilopedia entry

Historically, research in the area of warfare has seen the development of powerful new weapons closely followed by the development of defenses to counteract the weapons' destructive power. The development of nuclear weapons seemed to be the exception to this rule: for the first time, mankind had created a weapon to which there was apparently no effective defense. SDI (Strategic Defense Initiative), however, could be the answer to this problem. Using laser-equipped orbital satellites or ground-launched ABMs (Anti-Ballistic Missiles) to intercept and destroy enemy nuclear missiles in mid-air, the SDI Defense offers the first hope of negating the threat posed by nuclear missiles.

Modding

Main article: Modding (Civ2)/City improvements

The SDI Defense is defined on Line 18 of the @IMPROVE section of Rules.txt. Popup messages for successful interception, and thwarted sabotage, are defined in Game.txt at @SDI and @SABOTAGENO, respectively.

See also

• SDI Defense in other games

City improvements in Civilization II [edit]
Defense	City Walls Coastal Fortress SAM Missile Battery SDI Defense
Efficiency	Corruption	Courthouse Palace
	Pollution	Mass Transit Recycling Center
Growth	Food	Granary Harbor Supermarket
	Population	Aqueduct Sewer System
Happiness	Cathedral Colosseum Police Station Temple
Industry	Production	Factory Manufacturing Plant Offshore Platform
	Power	Hydro Plant Nuclear Plant Power Plant Solar Plant
Science	Research	Library Research Lab University
	Spaceship	SS Component SS Module SS Structural
Trade	Bank Capitalization Marketplace Stock Exchange Superhighways
Units	Airport Barracks Port Facility Transporter1
Related pages	List of improvements City Wonder
1 Only featured in Test of Time.