Hoping to tamp down a controversy growing around one of its best-known on-air personalities, NBC News on Tuesday suspended Brian Williams, the most-watched evening-news anchor in the U.S., from his duties as chief anchor and managing editor of “NBC Nightly News” for six months without pay in the wake of a scandal over misleading statements he made about his time covering the Iraq War in 2003.

The furor over Williams’ embellishments have engulfed NBC News since early last week, when his account of facing enemy fire while riding in a helicopter in 2003 was challenged by Iraq veterans. Williams’ last broadcast took place on Friday. Lester Holt will continue as substitute anchor.

NBC News has launched an internal probe of Williams’ statements about the Iraq helicopter incident as well as other reporting that has since been challenged, NBC News said in a statement released Tuesday evening.

“We have concerns about comments that occurred outside NBC News while Brian was talking about his experiences in the field,” NBC News president Deborah Turness said in a memo distributed Tuesday night.

Williams’ suspension was “severe and appropriate,” NBCUniversal CEO Steve Burke said in the statement, but he also asserted that Williams “deserves a second chance, and we are rooting for him” even though he called the anchor’s actions “inexcusable.”

The decision was made jointly by Turness; Pat Fili-Krushel, chairman of the NBCUniversal News Group, to whom Turness reports; and Burke.

At the heart of the matter is Williams’ falsification during several public appearances and on CBS’ “Late Show With David Letterman” of an incident that took place on a reporting trip to Iraq. A helicopter carrying Williams and his crew never came under fire, but a Chinook copter that was more than an hour ahead of that aircraft did. Williams by his own admission conflated the two air trips and made it seem as if he were under fire. Oddly enough, on a 2003 broadcast of “Dateline,” Williams reported the trip more or less accurately.

For NBCU the ramifications of his actions may be severe. Williams’ newscast has been the steadfast asset in NBCUniversal’s entire news portfolio. Its “Today” morning show remains in second place behind “Good Morning America” after ceding the top spot in 2012. “Meet the Press” is trying to gain traction after the ouster of one anchor, David Gregory, and the installation of another, Chuck Todd. Business-news network CNBC is struggling in daytime, so much so that the company said it will no longer do business with advertisers based on Nielsen ratings starting in the fourth quarter of this year. And MSNBC is trying to recalibrate itself in the wake of a ratings drop after thriving as a liberal-tilting news network.

Under Williams, “Nightly” has successfully fended off a challenge from ABC’s “World News.” With new anchor David Muir at its helm, that evening newscast has made strides in the audience most coveted by advertisers in news programming, adults 25-54. Whether “Nightly News” can fend off Muir in Williams’ absence remains to be seen.

In recent days, Williams’ ability to anchor the newscast was thrown into increasing degrees of doubt. News outlets began investigating any number of claims he made about past reporting exploits, including time spent covering Hurricane Katrina. Questions were raised about why NBC News had not forced Williams to stop telling the helicopter tale. And the propriety of having an anchor who lied about his own on-the-job actions telling the nation about developments in the world of politics and foreign affairs seemed skewed.

“While on Nightly News on Friday, January 30, 2015, Brian misrepresented events which occurred while he was covering the Iraq War in 2003. It then became clear that on other occasions Brian had done the same while telling that story in other venues. This was wrong and completely inappropriate for someone in Brian’s position,” Turness said in the memo.

NBC is essentially following a textbook play. When other TV-network correspondents have made serious gaffes, their networks have suspended either them or their producers, sometimes both. In some cases, the reporter must struggle to find normalcy.

Claims made in a 2004 edition of the now-defunct “60 Minutes II” newsmagazine about President George W. Bush’s service in the National Guard in the 1970s turned out to be based on documents that could not be authenticated. In the aftermath of that report, CBS set up an independent investigation, which led to the firing of the segment’s supervisor. Three other supervising execs were asked to resign. The report tarnished the reputation of CBS News anchor Dan Rather, who delivered the segment.

In 2013, CBS News suspended “60 Minutes” correspondent Lara Logan and a producer, Max McClellan, after a report they delivered on an Oct. 27 broadcast of the newsmagazine that year turned out to be based largely on the accounts of a source who provided inaccurate information. CBS made its decision after having Logan deliver an apology on air, and then investigating the process behind the report.

Williams has been a near-ubiquitous presence at NBC, making appearances on everything ranging from “Saturday Night Live” to “The Tonight Show Starring Jimmy Fallon.” For six months, at least, he will stay off the TV screen. All kinds of things can happen in half a year in the TV industry, and what happens at the end of Williams’ suspension remains to be seen.

Here is Turness’ full memo:

We have decided today to suspend Brian Williams as Managing Editor and Anchor of NBC Nightly News for six months. The suspension will be without pay and is effective immediately. We let Brian know of our decision earlier today. Lester Holt will continue to substitute Anchor the NBC Nightly News.

Our review, which is being led by Richard Esposito working closely with NBCUniversal General Counsel Kim Harris, is ongoing, but I think it is important to take you through our thought process in coming to this decision.

While on Nightly News on Friday, January 30, 2015, Brian misrepresented events which occurred while he was covering the Iraq War in 2003. It then became clear that on other occasions Brian had done the same while telling that story in other venues. This was wrong and completely inappropriate for someone in Brian’s position.

In addition, we have concerns about comments that occurred outside NBC News while Brian was talking about his experiences in the field.

As Managing Editor and Anchor of Nightly News, Brian has a responsibility to be truthful and to uphold the high standards of the news division at all times.

Steve Burke, Pat Fili and I came to this decision together. We felt it would have been wrong to disregard the good work Brian has done and the special relationship he has forged with our viewers over 22 years. Millions of Americans have turned to him every day, and he has been an important and well-respected part of our organization.

As I’m sure you understand, this was a very hard decision. Certainly there will be those who disagree. But we believe this suspension is the appropriate and proportionate action.

This has been a difficult time. But NBC News is bigger than this moment. You work so hard and dedicate yourselves each and every day to the important work of bringing trusted, credible news to our audience. Because of you, your loyalty, your dedication, NBC News is an organization we can – and should – all be proud of. We will get through this together.

Steve Burke asked me to share the following message.

“This has been a painful period for all concerned and we appreciate your patience while we gathered the available facts. By his actions, Brian has jeopardized the trust millions of Americans place in NBC News. His actions are inexcusable and this suspension is severe and appropriate. Brian’s life’s work is delivering the news. I know Brian loves his country, NBC News and his colleagues. He deserves a second chance and we are rooting for him. Brian has shared his deep remorse with me and he is committed to winning back everyone’s trust.”

Deborah