By Simon Lewis and Anna Voitenko KREMENCHUK, Ukraine (Reuters) – Already displaced from the frontline region of Kharkiv that has been partially occupied since Russia invaded Ukraine in February, Alia Skrypka, 35, believed that Kremenchuk, more than 170 km from the nearest fighting, was safe. But after a missile strike on a shopping mall killed at least 18 people in the central Ukrainian city on Monday, she is now considering whether she should move her two girls, Milla, 7 and Myroslava, 4, elsewhere – and perhaps even abroad. “After this, I’m not sure we are safe,” she said, after helping her …