U.S. Interior Secretary Ryan Zinke, who has aggressively sought to roll back Obama-era environmental protections, will be leaving his post at the end of the year, President Donald Trump tweeted Saturday, the latest high-profile departure from his administration.

Trump did not give a reason for Zinke’s departure. However, the former Navy Seal and ex-congressman from Montana has faced scrutiny of his use of security details, chartered flights and a real estate deal.

“Ryan has accomplished much during his tenure and I want to thank him for his service to our Nation,” Trump said on Twitter. “The Trump administration will be announcing the new secretary of the Interior next week.”

Zinke has run the Interior Department, which oversees America’s vast public lands, since early 2017. He has aggressively pursued Trump’s agenda to promote oil drilling and coal mining by expanding federal leasing, cutting royalty rates, and easing land protections despite environmental protests.

Zinke, 51, was among Trump’s most active Cabinet members, cutting huge wilderness national monuments in Utah to a fraction of their size and proposing offshore oil drilling in the Arctic, Pacific and Atlantic. He became a darling of the U.S. energy and mining industries and a prime target for conservationists and environmental groups.

In July, the Interior Department’s Office of Inspector General began investigating a Montana land deal between a foundation Zinke set up and a development group backed by the chairman of oil service company Halliburton Co, which has business with the Interior Department.

(SD-Agencies)