These are the multiplayer factions in Modern Warfare 2:
| Task Force 141 |
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A multinational grouping of military units or forces for the performance of a specific operation or assignment. |
| US Army Rangers |
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A military Special Forces Unit of the United States Army. The Regiment is composed of rapidly-deployable light infantry forces with specialized skills that enable them to perform a variety of special operations missions. |
| Op For |
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An opposing enemy force. |
| Spetsnaz / Ultranationalists |
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Russian Army Special Forces, are the original Spetsnaz and are generally considered the best trained units of the Armed Forces of the Russian Federation. |
| Militia |
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Rebellion faction in Rio de Janeiro. |
| Navy SEALs |
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Navy SEALs |