Feinstein covering for Gorelick suggesting there was no law at that time?
FISA had no physical search provision, therefore there was no legal mechanism to get a warrant for physical entry. At the time, FISA did have a provision for an electronic surveillance warrant, and one of those -WAS- obtained.
Since then, FISA has been extended, and now has facilities for making physical entry under a warrant, and for making physical entry without a warrant.