Berlin's mayor has a powerful message for Donald Trump about his border wall with Mexico

The mayor of Berlin, a city intimately aware of the lasting damage wrought by building walls, said in a powerful message to President Donald Trump on Friday that he could not “silently look on as a country sets about building a new wall.”

“We can simply not accept that all our historic experiences are being thrown into disarray by the ones we have to thank most for our freedom: the Americans,” Governing Mayor Michael Müller said of the Berlin Wall in a statement posted on the City of Berlin’s official website and translated by the Washington Post. “I call on the US president to not go down this wrong track of isolation and exclusion.”

As the Post points out, Nov. 9, 2016–the day after Trump was elected president–was the 27th anniversary of the fall of the Berlin Wall.

The Berlin Wall divided Soviet-controlled East Berlin from West Berlin, which was governed by American, British, and French forces between 1961 and 1989.

During a speech at the Brandenburg Gate, a former symbol of the divided city, President Ronald Reagan famously demanded that Soviet leader Mikhail Gorbachev “tear down this wall!”

Echoing the famous 1987 speech, Müller ended the statement by addressing Trump in English. “Dear Mr. President, don’t build this wall!”

In his first week in office, Trump has doubled-down on his campaign promise to build a large border wall separating Mexico and the United States by signing executive orders to build the wall and crack down on immigration. White House spokesman Sean Spicer has said that a 20% tax on imports from Mexico was one way being considered to pay for the wall–an idea that officials later walked back.

For now, both Trump and Mexican President Enrique Peña Nieto have agreed “not to speak publicly” about their differing opinions about the wall and how it will be funded, according to a Mexican government press release.