FILE - German Chancellor Angela Merkel, left, and British Prime Minister David Cameron shake hands after a news conference following a meeting at the chancellery in Berlin, Germany, Friday, May 29, 2015. (AP Photo/Markus Schreiber, File)

File - German Chancellor Angela Merkel is pictured with light and shadow at the Meseberg palace near Berlin, Germany, Thursday, Jan. 23, 2014. (AP Photo/Michael Sohn, File)

FILE - German Chancellor Angela Merkel, right, and British Prime Minister David Cameron brief the media after meeting at the chancellery in Berlin, Germany, Friday, May 29, 2015. (AP Photo/Markus Schreiber, File)

FILE - President Donald Trump and German Chancellor Angela Merkel shake hands following their joint news conference in the East Room of the White House in Washington, Friday, March 17, 2017. (AP Photo/Pablo Martinez Monsivais, File)

FILE - German Chancellor Angela Merkel and Russian President Vladimir Putin, look on as Putin's dog Cony walks past, during the meeting in Putin's residence in the Russian Black Sea resort of Sochi, Sunday, Jan. 21, 2007. (AP Photo/Mikhail Metzel, File)

FILE - U.S. President Barack Obama, left, is welcomed by German Chancellor Angela Merkel prior to a meeting in the chancellery in Berlin, Germany, Thursday, Nov. 17, 2016. (AP Photo/Michael Sohn, File)