- Under Secretary of Defense for Acquisition and Sustainment
- Under Secretary of Defense for Intelligence
- Under Secretary of Defense for Personnel and Readiness
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- Uniejów Castle
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- Union of Arras
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- Union of Cities
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- Union of Lithuanian Freedom Fighters
- Union of Lublin
- Union of Mujahadin
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- Union of Resistance Forces
- Union of Retaliation
- Union of South Africa Commemoration Medal
- Union of South Africa King's Medal for Bravery
- Union of South Africa King's Medal for Bravery, Gold
- Union of South Africa King's Medal for Bravery, Silver
- Union of South Africa Queen's Medal for Bravery, Gold
- Union of South Africa Queen's Medal for Bravery, Silver
- Union of Transylvania with Romania
- Union of Utrecht
- Union of the Committees of Soldiers' Mothers of Russia
- Union sacrée
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- Unit Ei 1644
- Unit Identification Code
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- Unit citation
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- Unitas Medal
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- United Nations Mission in Côte d'Ivoire
- United Nations Mission in East Timor
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