at the end of Broken Steel you are pretty much under the assumption only small bands of remnants remain of the Enclave.
In the US, but it is possible if those blinking lights and littl markers on the map did mean something, it could mean that the Enclave still has well sized forces, just in another nation. But in the US, their probably scattered and lost without a leader. But maybe its possible, that the Enclave forces in other countries (If any) are scattered and lost as well?
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There's no reason to doubt the Encalve COULD have forces in other countries. I mean the Enclave was a top secret government orginization, with alot of fingers. So the possability that the Enclave does have forces in other nations, whether scattered or orginized is still to be discovered.