Under Islamic law, what is the primary condition that permits defensive military Jihad?

1. To convert non-Muslims
2. To gain wealth and resources
3. When Muslims are persecuted or driven from their homes
4. To expand territorial borders

Islamic jurisprudence permits defensive military action under strict conditions. The primary justification is when a Muslim community faces persecution, oppression, or is forced from their homes. This is derived from Quranic verses like 22:39-40, which permit fighting for those who have been wronged. Aggression for conversion, wealth, or expansion is strictly prohibited.