Rio Tinto owns 18.1 million shares of Northern Dynasty through its QIT-Fer et Titane Inc. subsidiary.
Northern Dynasty is developing the Pebble project in the Bristol Bay region of southwest Alaska.
"As part of its review, Rio Tinto will consider the Pebble Project's fit with the group's strategy of investing in and operating long life and expandable assets, and with the strategy for its copper business," Rio Tinto said.
Earlier this month, Northern Dynasty exercised its right to acquire Anglo American (US) Pebble LLC's sake in the Pebble Limited Partnership to re-acquire 100 per cent ownership and control of the project.
Shares in Northern Dynasty were down 17 cents at $1.61 in trading on the Toronto Stock Exchange on Monday.