NBC News will announce a significant reorganization of its leadership ranks, along with a major investment in a European TV network, a person briefed on the changes said Tuesday.

Noah Oppenheim, the executive in charge of “Today,” will become NBC News’ new president, the person said. The NBC News chairman, Andrew Lack, will announce the changes to staff members Tuesday afternoon.

Oppenheim will replace Deborah Turness, the top female executive in TV news, who will be moved into a new position — president of NBC News International — where she will be the news chief of the new European network, called Euronews.

NBC’s 25 percent stake in Euronews means that the network can, at long last, tap into an international market. This will enable it to compete more aggressively with CNN, which has a robust international presence (Euronews will be renamed Euronews NBC). Founded in 1993, the network has more than 400 journalists and is broadcast in 12 languages.

Euronews has a wide footprint — it reaches 277 million households across Europe, Africa and the Middle East — but its viewership is small. NBC spent roughly $30 million for its stake in the network, according to the person briefed on the plan.

Lack’s announcement comes just two years after NBC had reached a low point at its news division. The network was dealing with a crisis involving Brian Williams, the “NBC Nightly News” anchor; “Today” was consistently losing to “Good Morning America”; and MSNBC’s ratings were plummeting.

Lack, who ran NBC in the 1990s, returned several months later and has worked to stabilize the division.

Oppenheim took over “Today” in June 2015 and brought a steady hand to the show following the short-lived and tumultuous run of Jamie Horowitz.

Under his leadership, “Today” returned to the No. 1 morning show in the 25-to-54-year-old demographic important to news program advertisers. It has defeated ABC’s “Good Morning America” in the category for more than a year — 59 consecutive weeks of wins.