AMSTERDAM — Flags flew at half-staff Friday in this small but extremely international country, one that is accustomed to standing on the forefront of global cultural debates over such things as gay rights, euthanasia and marijuana policies. But on Thursday, after the downing of Malaysia Airlines Flight 17, the Netherlands found itself thrust squarely into an unaccustomed role at the center of the realpolitik of the conflict in Ukraine.

It seemed as if everyone in the Netherlands, a country of 16 million people, knew someone among the 189 Dutch nationals killed in the crash, whether personally, or as a friend of a friend, or simply by the familiarity of celebrity, as with Senator Willem Witteveen and the AIDS specialist Joep Lange.

Like Dr. Lange, a scientist, many of those on board were activists traveling to AIDS 2014, an international conference in Melbourne, Australia, at which former President Bill Clinton is scheduled to speak. There were many others, of course: a florist couple on vacation; a young employee of the human rights organization Amnesty International; children accompanying their parents on holiday excursions. All were sad testaments to one of the worst plane disasters in the country’s history.