U.S. first lady Melania Trump returned to the international stage Wednesday as she mingled with the spouses of America's closest allies over classical music, fashion and chocolate.\r\nAs President Donald Trump harangued Germany and other allies at a NATO summit in Brussels, his wife chatted amiably with some of their spouses at a music conservatory in a wooded park in Waterloo, near the Belgian capital.\r\nThere, she and 10 other spouses were given a tour of the Queen Elisabeth Music Chapel, a training center for gifted young musicians housed in a modernistic glass building.\r\nMrs. Trump, 48, wore a navy blue sleeveless Calvin Klein calf-length dress with white and green detail on one collarbone and white Christian Louboutin heels with their trademark red soles. Klein is an all-American fashion house, but its chief creative officer, Raf Simons, is Belgian.\r\nIn the evening, she changed into a sleeveless white Elie Saab cocktail dress for a dinner at the Art and History Museum at the Cinquantenaire, a landmark city park.\r\nNeither of the Trumps took a drink as they chatted with other heads of state at a cocktail reception, only hours after the U.S. president accused Germany of being "captive to Russia" for buying natural gas from that country and chided other allies for their levels of defense spending. The president does not drink alcohol.\r\nHolding hands, the Trumps next walked up the steps of the museum, where the president joined leaders for a working dinner and the first lady joined a separate dinner for spouses.\r\nThe trip marked the former model's return to the international stage after she dropped out of public sight in May for nearly a month, including five days in the hospital following surgery for a benign kidney condition. Her husband later told reporters that she had had a "big operation" and was under doctors' orders not to fly for a month.\r\nHer office clarified that only international travel was forbidden for that period of time, and the first lady did not accompany the president to Canada for an earlier world leaders' summit or to Singapore for his historic one-on-one meeting with North Korean leader Kim Jong Un, both in the first half of June.\r\nThere was no word on how Mrs. Trump would spend her second day in Brussels. The couple travels next to Britain, where planned engagements include tea with Queen Elizabeth, and to Helsinki, Finland, where the U.S. president is to hold a summit with Russian President Vladimir Putin.\r\nAs the spouses arrived at the music academy in the early afternoon, they were greeted by Amelie Derbaudrenghien, the partner of Belgian Prime Minister Charles Michel, and Ingrid Schulerud, the wife of NATO Secretary-General Jens Stoltenberg.\r\nThey were then escorted into a music auditorium with tall glass windows offering views into the woods behind the school for performances of Tchaikovsky's Valse Scherzo and music by Hubay and Piazzolla.\r\nDuring an intermission they posed for a group photo, viewed a display of hats by Belgian designer Fabienne Delvigne and were offered delicacies created by Herman Van Dender, a pastry maker and chocolatier who is the official supplier to the Belgian royal house.\r\nMrs. Trump sat between French first lady Brigitte Macron, who was dressed in white, and Derbaudrenghien, in vibrant yellow, during the concert. Other participating first ladies included Emine Erdogan of Turkey and Mojca Stropnik of Slovenia, Mrs. Trump's native country. Gauthier Destenay, the husband of Luxembourg's Prime Minister Xavier Bettel, was the only man in the group.\r\nAt one point during the concert, Mrs. Trump and some of the others applauded prematurely. Catching themselves, they smiled and kept on listening.