Fuse ESB supports deploying WAR directly.
There is a WAR url handler supporting this
Currently to my knowledge FAB is not supporting WARs per see. But it may be improved for that in the future.
But its an interesting idea (IMHO) to developer as a regular WAR app, which you could essentially also quickly run using mvn jetty:run, mvn camel:run etc. And then deploy as FAB in Fuse ESB (eg to allow to share dependencies) where was WAR would be an isolated application.