What was the main reason for launching Operation Allied Force?

The main reason for launching Operation Allied Force was to end the oppression of ethnic Albanians by the Serbian government. The operation, which took place in 1999, was a NATO-led military campaign aimed at stopping the humanitarian crisis and severe violations of human rights in Kosovo, where Serbian forces were committing acts of violence against the ethnic Albanian population. This intervention marked a significant moment in international relations as it focused on the protection of civilians and was executed without the authorization of the United Nations, highlighting the importance of humanitarian intervention in global conflicts.

The other options, while related to significant events in U.S. military history, do not pertain specifically to the motivations behind Operation Allied Force. There were no humanitarian efforts in Somalia associated with this operation, support for U.S. troops in Iraq was a separate context, and the responses to the September 11 attacks occurred in a different timeframe and were driven by distinct motivations and actions.