保卫 (bǎo wèi) means 'to defend, to safeguard' and is used for protecting something important (territory, peace, security) from external threats, often with military or official force. It is stronger and more formal than 保护 (bǎo hù 'to protect'), which is a general everyday word. Unlike 维护 (wéi hù), which focuses on maintaining rights or relationships, 保卫 emphasizes warding off danger.