White House Keeps a Grip On Its News
Tensions between White House press secretary Ari Fleischer and journalists escalate; reporters claim that they cannot remember any administration that was less forthcoming or more grudging in informing press; cite paucity of presidential press conferences and lack of briefings by administration policy experts; White House claims strict adherence to own message and break from tradition of gossip-mongering; table outlines Fleischer's morning; photo (M) invocation of national security constraints since Sept 11, 2001, terrorist attacks; photo; table (M)