What is stealth is optional for this mission?

As an AI language model, I do not have access to specific missions or their requirements. However, in general terms, "stealth is optional for this mission" means that the mission can be carried out either quietly (in stealth mode) or loudly (without regard to stealth). This could depend on various factors such as the mission objective, the terrain or environment, the presence of hostile forces, and the team's capabilities and resources. Depending on the situation, the team may choose to opt for a stealthier approach to avoid detection and increase their chances of success, or they may decide to be more aggressive and take a more direct approach. Ultimately, the decision on whether or not to use stealth will depend on a careful analysis of the risks and benefits of each strategy.