Does a Master Assassin sent out on a Mediterranean defense mission leave their den vulnerable to Templar attack?

As the question says, if I send a Master Assassin off on a Mediterranean defense mission, does it leave their assigned den vulnerable to a Templar attack?

When I get my 7 dens all assigned Master Assassins, can I risk using them for Mediterranean defense missions and still be safe from Templar attacks?

Solution 1:

No. Not for regular missions or even if you station them in a city. They will remain den masters there and your dens will be protected. Though keep in mind, if they are killed in their missions, the den will (probably) be unprotected and will have to assign another one to the respective den and train to master. I don't know what happens in this case but you probably won't have to do the associated missions again.