"The U.S. ambassador to Estonia stepping down in protest to president Trump destroying U.S.-European relations is another example of someone who spent decades building the relations between Europe and the U.S. not being able to bear the speed at which Trump is thrashing cooperation in the democratic world," Paet told the Baltic News Service on Saturday.

"Trump's recent claims that the European Union was created to use the U.S. and attack the piggy bank of the U.S., or that NATO is something similar to NAFTA, show that Trump doesn't understand and doesn't want to understand the nature of the decades-long partnership of the U.S. and Europe, and the European Union," he added.

Urmas Paet (Reform/ALDE) served as Estonia's minister of foreign affairs from 2005 to 2014 throughout all of then-Prime Minister Andrus Ansip's three cabinets.

"It is completely understandable that people can't just stand by, but that they are leaving the U.S. foreign service, like the ambassador to Estonia and several of his colleagues," Paet said. "Trump's verbal, political and economic attacks against the EU and EU-U.S. relations have done substantial damage to the trust between Europe and the United States as well as the two sides' practical cooperation. Trump's actions have also divided U.S. society," he added.

Paet named the trade war with Europe and other Western allies, public actions against the internal cooperation and unity of the EU as well as backing down from decisions made together at the G7 meeting as just a few examples of Trump's recent actions that jeopardise transatlantic cooperation.

U.S. Ambassador to Estonia James D. Melville announced on social media late on Friday that he is resigning, effective 29 July. This makes him the third ambassador in the last 12 months to leave the State Department early. He is among many senior State Department officials who have headed for the exits or been pushed toward them since Trump assumed office, CNN said.

"For the President to say the EU was 'set up to take advantage of the United States, to attack our piggy bank,' or that 'NATO is as bad as NAFTA' is not only factually wrong, but proves to me that it's time to go," Melville wrote in a note to friends on social media.

"I suppose this is as good a time as any to tell my friends that I'm leaving Estonia one month from today, on July 29, to retire from the Foreign Service and begin life as a private citizen after 33 years of public service. I've always admired the professionalism of my colleagues in supporting U.S. Government policy as articulated and directed by our elected leaders and their administrations, without regard to partisan politics," Melville wrote.

"Having served under six presidents and 11 secretaries of state, I never really thought it would reach that point for me," he added. Melville was appointed ambassador to Estonia in 2015.