11:45 a.m. NEW YORK -- The timing could hardly be better.

''News War'' is a ''Frontline'' probe into the modern Fourth Estate, embattled from many directions. And, by chance, it coincides with the imminent conclusion to a Washington free-for-all that has ensnared the news media: the perjury trial of former vice presidential aide I. Lewis ''Scooter'' Libby. He is charged with lying to investigators about his conversations with journalists such as Judith Miller, the New York Times reporter who spent 85 days in jail in a futile effort to avoid revealing such conversations.

The first hour of the four-part series does a splendid job of untangling the snarl of events that began in early 2003 with the Bush administration's successful drive to win support from the public, and the media, for invading Iraq.

Airing Tuesday on PBS at 9 p.m. EST (check local listings), ''Secrets, Sources & Spin'' lays out how the government peddled its point of view to major media outlets by planting confidential tips that supported administration claims about Iraqi weapons of mass destruction. Such tips sparked stories which the government then cited as bolstering its claim.

Few in the media broke this information loop at the time, nor managed to uncover what became obvious only after the invasion: There were no WMDs.

''The way that the press was sold and spun ... and just fooled by the White House in the run-up to the war represents more than just a missed story,'' media analyst Jay Rosen says in the film. ''How can one say that we have a watchdog press after a performance like that?''

But this represents just one battle for ''News War,'' in which investigative journalist Lowell Bergman, a Pulitzer Prize-winning reporter whose expose for CBS' ''60 Minutes'' was dramatized in the film ''The Insider,'' finds the news media locked in a protracted conflict with the White House and much of government. It's a conflict that reaches back four decades to the Nixon administration, which famously warred with the news media before being undone by The Washington Post's exposure of the Watergate scandal.

On Feb. 20, ''Secrets, Sources & Spin'' continues with an inquiry into how much the press can reveal about secret government programs in the war on terror without jeopardizing national security.

It also looks at the pressures on reporters who protect a confidential source under far less threatening circumstances. San Francisco Chronicle reporters Lance Williams and Mark Fainaru-Wada were ruled in contempt of court for refusing to reveal the source of leaked grand jury transcripts in a steroid distribution case - even though their reporting on how sports stars have taken performance-enhancing drugs won awards, added an asterisk to the career of home run king Barry Bonds and was hailed by President Bush.

''The bottom line is: What should the news media be allowed to do? What privileges should it have?'' said Bergman in a phone interview earlier this week. ''Is a conversation with a reporter similar to your conversation with your doctor or your spouse,'' where confidentiality is legally protected and widely supported?

Summing up his series, Bergman said, ''We're looking at the issues of confidential sources, national security reporting, and the changing economic model for the news industry.''

When the former two issues emerged decades ago, he added, ''the major media were primarily news magazines, metropolitan newspapers and the three TV networks. And they were on the rise from an economic point of view.''

Today, the media landscape is shifting rapidly, and no one knows what it will eventually look like. With new technologies and a ''democratization'' of reporting shaking things up - and raising uncertainties about the business model of traditional media - just how bold will those mainstream media be in pursuing their longtime role as the public's surrogate?

Bergman is currently a professor of investigative journalism at the University of California, Berkeley. Speaking from California, he was about to board a plane for Boston, where he would finish a series that's been in the works for two years, but whose subject matter is still changing under his feet.

On Feb. 27, ''What's Happening to the News'' looks ahead to the future awaiting the news media. America's major network news divisions and daily newspapers face mounting pressure for profits from corporate owners as well as growing challenges from new technologies, notably the Internet, which is transforming the very definition of news.

Finally, on March 27, ''Stories From a Small Planet'' looks at media around the globe to reveal the international forces that influence journalism and politics in the United States. This segment focuses on Al-Jazeera TV and how it has changed the face of Arab media, while gaining influence around the world.

Supplementing the ''News War'' series will be a robust Web site with additional interviews and other resources that ''would have ended up in cardboard boxes'' in a past media age, as Bergman noted.

The media world today is under siege by government, the marketplace and even members of the audience the media claim to serve.

According to Bergman, the overarching question ''News War'' raises is, ''What do you expect out of your news media?'' But another follows right on its heels: In the emerging new world, can those expectations be met?

On the Net:

http://www.pbs.org/frontline/newswar

EDITOR'S NOTE _ Frazier Moore is a national television columnist for The Associated Press. He can be reached at fmoore(at)ap.org