When President Trump welcomes German Chancellor Angela Merkel to Washington on Friday, he will begin a new and potentially chillier relationship between the long-serving German leader and the third U.S. president to occupy the White House during her tenure.

Barack Obama and George W. Bush both enjoyed notably close relationships with Merkel during their presidencies. Obama’s final phone call to a world leader went to Merkel in January, during which he thanked her and her husband for their personal friendship over the previous eight years.