U.S. President Donald Trump said on Sunday that White House Council of Economic Advisers Chairman Kevin Hassett will "shortly" leave his post, but did not provide a reason for the latest high-level departure from the administration.

"Kevin Hassett, who has done such a great job for me and the Administration, will be leaving shortly. His very talented replacement will be named as soon as I get back to the U.S.," Trump said in a Twitter post on Sunday night as he flew to Europe for a series of state visits.

Trump tweet: Kevin Hassett, who has done such a great job for me and the Administration, will be leaving shortly. His very talented replacement will be named as soon as I get back to the U.S. I want to thank Kevin for all he has done - he is a true friend!

Hassett's impending departure comes at a time of drama between the United States and some of its main trade partners. A trade war is brewing between the United States and China, while Trump has vowed to impose punitive tariffs on all Mexican goods in an intensifying dispute over migration.

Hassett previously served as a scholar of fiscal policy at the conservative American Enterprise Institute think tank before Trump nominated him to the White House role in 2017.

In the White House post, he worked with Trump's senior advisor and son-in-law Jared Kushner on a proposed immigration plan that the Republican president unveiled in May and had backed a U.S. move to end waivers of sanctions for countries that buy Iranian oil.

Trump thanked Hassett for his work, and called him a "true friend" in the Twitter post on Sunday. He did not give any indication on who he would name to replace Hassett.

Hassett is poised to become the latest in a long line of senior White House officials and Cabinet secretaries to depart the administration since Trump took office in January 2017.