A Ukrainian serviceman enters a shelter at the frontline positions near Zolote, Ukraine, Monday, Feb. 7, 2022. The buildup of over 100,000 Russian troops near Ukraine has fueled Western worries of a possible offensive. White House national security adviser Jake Sullivan warned Sunday that Russia could invade Ukraine "any day," triggering a conflict that would come at an "enormous human cost." (AP Photo/Evgeniy Maloletka)