[nbraud]

Ah, ok, you were referring to the DoS vector.

Yes, a simultaneous seizure of the DirAuth would do that, breaking Tor relays and clients until the software is updated (the list is in src/or/config.c if you are curious).

On the other hand, it's a move that would require international cooperation <i>and</i> cost lots of political capital, whose only result would be a temporary (but global) DoS.