The Russian-speaking widow was born in Latvia 63 years ago, when it was still a part of the Soviet Union, got married there and raised a family. She has never lived anywhere else.So it came as a nasty surprise this fall when she received a curt official letter saying she had lost her rights to residency, a state pension and medical care. “You must leave the territory of the Republic of Latvia by Nov. 30, 2023,” she was informed.With nowhere to go, the widow, Nina Marcinkevica, who has heart and lung problems and high blood pressure, said she collapsed from shock and spent the next three days in bed weeping.

Ms. Marcinkevica’s home in the mostly Russian-speaking city of Daugavpils, in eastern Latvia, is more than 600 miles from the front line in Ukraine and entirely peaceful.

Janis Dombrava is a nationalist member of Latvia’s Parliament who has seized on the Ukraine war to whip up hostility toward Russian speakers and push through legislation targeting them. In an interview in Riga, the capital, he said Russia’s actions in Ukraine had exposed the risks of harboring a “fifth column” that does not speak the national language, gets its information from Russian news media and often tilts to Moscow’s view of the world. “We can keep those who want to integrate but not those who are waiting for the return of the Soviet Union. They should leave,” said Mr. Dombrava, a leader of the National Alliance, a grouping of nationalist parties, and a chairman of Parliament’s national security committee.