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Military glossary - Letter I


Igloo space
(DOD) Area in an earth-covered structure of concrete and/or steel designed for the storage of ammunition and explosives.

Image motion compensation
(DOD, NATO) Movement intentionally imparted to film at such a rate as to compensate for the forward motion of an air or space vehicle when photographing ground objects.

See imagery intelligence.

Immediate mission request
(DOD) A request for an air strike on a target which, by its nature, could not be identified sufficiently in advance to permit detailed mission coordination and planning.

Impact action fuze
(DOD, NATO) A fuze that is set in action by the striking of a projectile or bomb against an object, e.g., percussion fuze, contact fuze. Synonymous with direct action fuze.

Improved conventional munitions
(DOD) Munitions characterized by the delivery of two or more antipersonnel or antimateriel and/or antiarmor submunitions by an artillery warhead or projectile.

Inactive aircraft inventory
(DOD) Aircraft in storage or bailment and/or government-furnished equipment on loan or lease outside of the Defense establishment or otherwise not available to the Military Services.

(DOD) In information operations, an assessed event of attempted entry, unauthorized entry, or an information attack on an automated information system. It includes unauthorized probing and browsing; disruption or denial of service; altered or destroyed input, processing, storage, or output of information; or changes to information system hardware, firmware, or software characteristics with or without the users' knowledge, instruction, or intent.

Indefinite delivery type contract
(DOD) A type of contract used for procurements where the exact time of delivery is not known at time of contracting.

Indicated airspeed hold mode
(DOD) In a flight control system, a control mode in which desired indicated airspeed of an aircraft is maintained automatically.

Indirect laying
(DOD, NATO) Aiming a gun either by sighting at a fixed object, called the aiming point, instead of the target or by using a means of pointing other than a sight, such as a gun director, when the target cannot be seen from the gun position.

Individual mobilization augmentee detachment
(DOD) A dependent not entitled to travel to the overseas command at Government expense or who enters the command without endorsement of the appropriate overseas commander.

Industrial preparedness program
(DOD) Plans, actions, or measures for the transformation of the industrial base, both government-owned and civilian-owned, from its peacetime activity to the emergency program necessary to support the national military objectives. It includes industrial preparedness measures such as modernization, expansion, and preservation of the production facilities and contributory items and services for planning with industry.

Inertial navigation system
(DOD, NATO) A self-contained navigation system using inertial detectors, which automatically provides vehicle position, heading, and velocity.

Influence release sinker
(DOD, NATO) A sinker which holds a moored or rising mine at the sea-bed and releases it when actuated by a suitable ship influence.

Information superiority
(DOD) The capability to collect, process, and disseminate an uninterruped flow of information while exploiting or denying an adversary's ability to do the same.

See information security.

See Inactive National Guard.

Initial entry into Military Service
(DOD) Entry for the first time into military status (active duty or reserve) by induction, enlistment, or appointment in any Service of the Armed Forces of the United States. Appointment may be as a commissioned or warrant officer; as a cadet or midshipman at the Service academy of one of the armed forces; or as a midshipman, US Naval Reserve, for US Naval Reserve Officers' Training Corps training at a civilian institution.

Initial path sweeping
(DOD, NATO) In naval mine warfare, initial sweeping to clear a path through a mined area dangerous to the following mine sweepers.

Initial provisioning
(DOD) The process of determining the range and quantity of items (i.e., spares and repair parts, special tools, test equipment, and support equipment) required to support and maintain an item for an initial period of service. Its phases include the identification of items of supply, the establishment of data for catalog, technical manual, and allowance list preparation, and the preparation of instructions to assure delivery of necessary support items with related end articles.

Initial unloading period
(DOD, NATO) In amphibious operations, that part of the ship-to-shore movement in which unloading is primarily tactical in character and must be instantly responsive to landing force requirements. All elements intended to land during this period are serialized.

Initiation of procurement action
(DOD) That point in time when the approved document requesting procurement and citing funds is forwarded to the procuring activity.

Inshore patrol
(DOD, NATO) A naval defense patrol operating generally within a naval defense coastal area and comprising all elements of harbor defenses, the coastal lookout system, patrol craft supporting bases, aircraft, and Coast Guard stations.

Instrument approach procedure
(DOD, NATO) A series of predetermined maneuvers for the orderly transfer of an aircraft under instrument flight conditions from the beginning of the initial approach to a landing or to a point from which a landing may be made visually or the missed approach procedure is initiated.

Integrated fire control system
(DOD) A system which performs the functions of target acquisition, tracking, data computation, and engagement control, primarily using electronic means assisted by electromechanical devices.

Integrated tactical warning
See tactical warning.

Intelligence contingency funds
(DOD) Appropriated funds to be used for intelligence activities when the use of other funds is not applicable or would either jeopardize or impede the mission of the intelligence unit.

Intelligence data handling systems
(DOD) Information systems that process and manipulate raw information and intelligence data as required. They are characterized by the application of general purpose computers, peripheral equipment, and automated storage and retrieval equipment for documents and photographs. While automation is a distinguishing characteristic of intelligence data handling systems, individual system components may be either automated or manually operated.

Intelligence preparation of the battlespace
(DOD) An analytical methodology employed to reduce uncertainties concerning the enemy, environment, and terrain for all types of operations. Intelligence preparation of the battlespace builds an extensive data base for each potential area in which a unit may be required to operate. The data base is then analyzed in detail to determine the impact of the enemy, environment, and terrain on operations and presents it in graphic form. Intelligence preparation of the battlespace is a continuing process.

Intelligence subject code
(DOD) A system of subject and area references to index the information contained in intelligence reports as required by a general intelligence document reference service.

Interagency coordination
(DOD) Within the context of Department of Defense involvement, the coordination that occurs between elements of the Department of Defense and engaged US Government agencies, nongovernmental organizations, private voluntary organizations, and regional and international organizations for the purpose of accomplishing an objective.

Intercontinental ballistic missile
(DOD) A ballistic missile with a range capability from about 3,000 to 8,000 nautical miles.

Interim JTIDS message specification
See tactical digital information link.

Intermediate marker (land mine warfare)
(DOD, NATO) A marker, natural, artificial or specially installed, which is used as a point of reference between the landmark and the minefield.

International arms control organization
(DOD) An appropriately constituted organization established to supervise and verify the implementation of arms control measures.

International loading gauge (GIC)
(DOD, NATO) The loading gauge upon which international railway agreements are based. A load whose dimensions fall within the limits of this gauge may move without restriction on most of the railways of Continental Western Europe.

Intracoastal sealift
(DOD) Shipping used primarily for the carriage of personnel and/or cargo along a coast or into river ports to support operations within a given area.

See information operations.

(DOD) See isolated personnel report.