Historical Background:
“A timeline of the tensions between Russia and Ukraine” - The New York Times
“North Atlantic Treaty Organization (NATO), 1949” [A background essay on the history of the North Atlantic Treaty Organization] - (US State Department)
Map of NATO member nations - From NATO’s website
“How Putin Controls Russia” (The New Yorker)
Map of Europe During the Cold War - Google Arts & Culture
Four Maps That Explain the Russia-Ukraine Conflict - (The Washington Post)
Russia & Ukraine - The Tangled History that Connects (National Geographic)
Russia's at War with Ukraine - Timeline (NPR)
Russia’s war in Ukraine: complete guide in maps, video and pictures (The Guardian)
"To Grasp What's Going on at the Russia-Ukraine Border, It Helps to Know Some History" (NPR)
"The Roots of Ukraine's War: How the Crisis Developed" (NYT)
Information About Ukraine:
“Ukraine” - World History in Context
“Ukraine” - CIA World Factbook
“The History of Ukraine in Five Minutes” - [from 2014] Sky News
Information About Russia:
“Post-Soviet Russia” - World History in Context
“Russia” - CIA World Factbook
Many of these sources are running live updates
BBC News - Ukraine Crisis Page
Reuters - Ukraine and Russia Page
With sincere thanks to the wonderful librarians at the Association of Independent School Librarians.