U.S. Interior Secretary Ryan Zinke will be leaving his post at the end of the year after serving for almost two years, U.S. President Donald Trump tweeted on Saturday, the latest high-profile departure from Trump’s administration.

Trump did not give a reason for Zinke's departure. However, the former Navy Seal and ex-congressman from Montana has come under scrutiny for 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," he added.

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

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.

Critics also questioned Zinke's ethics and some of his moves triggered government investigations.