The top US diplomat for European affairs, Wess Mitchell, has resigned, according to his resignation letter seen by Reuters on Tuesday at a time of strains in the trans-Atlantic relationship over US President Donald Trump's policies. In the letter to US Secretary of State Mike Pompeo dated Jan. 4, Mitchell said he felt he had completed his goals for the post and wanted to spend more time with his young family.

He will leave the post on Feb. 15, according to the State Department. There were no obvious signs that Mitchell, a former policy analyst on central and eastern Europe, was resigning out of protest against Trump administration policies. Mitchell was brought on board by former Secretary of State Rex Tillerson in 2017 as Trump threatened to withdraw the United States from the NATO military alliance and Washington accused Moscow of meddling in the 2016 US presidential campaign.

The trans-Atlantic relationship has been further strained by Trump's decisions to impose US tariffs on European steel and aluminum, pull out of the Iran nuclear deal and global climate pact, and recently to withdraw troops from Syria.

Copyright Reuters, 2019