From Russia's massing of soldiers along the border in November to Vladimir Putin ordering troops into eastern separatist areas, here is a timeline of months of tensions around Ukraine.
Oil prices surged close to $100 per barrel Tuesday as major crude producer Russia prepared to send troops into two breakaway regions of Ukraine, sparking Western nations to ready economic sanctions against Moscow.
Ukrainian President Volodymyr Zelensky, after a phonecall Sunday with his French counterpart Emmanuel Macron, called for a resumption of talks with Russia under OSCE auspices and an immediate ceasefire.
Russia and Belarus are extending military drills that were due to end on Sunday, the Belarus defence minister said, in a step that further intensifies pressure on Ukraine as Western leaders warn of an imminent Russian invasion.
Shellfire rang out in eastern Ukraine on Friday as the army and Moscow-backed separatists accused each other of provocations and US warnings of an imminent Russian invasion stoked international tension.