President Sauli Niinistö of Finland played a passive-aggressive game with Donald Trump on Wednesday at the White House, peppering a joint press conference with jabs subtle enough to fly under his radar. Trump, preoccupied with spitting nails over House Democrats' latest impeachment development, hardly seemed to notice. Niinistö described his time browsing Washington's sprawling museums, noting the Smithsonian Institution's traditionalist American history collection and a ceremony he witnessed at Arlington National Cemetary. He also heaped praise on the National Museum of the American Indian and the still new-ish National Museum of African American History and Culture, spotlighting racial diversity and...