Map shows territory currently held by pro-Russian rebels
Protests erupted in Ukraine’s capital Kiev in November 2013 after pro-Moscow President Viktor Yanukovych trashed a deal offering closer EU ties, and instead moved closer to Russia.
The protests spread fast and intensified, worsening divisions between Ukrainian speakers in the east and Russian speakers in the west that have existed since the collapse of the Soviet Union in 1991.
Three months later rebels seized government buildings in the Crimean capital Simferopol and within days declared a referendum on joining Russia. In March, 97 per cent of voters reportedly backed the proposal.
Unrest soon spread to Donetsk and Luhansk in eastern Ukraine, with rebels occupying government buildings in April and taking control.
Pro-Russian rebels declared the independence of Donetsk and Luhansk in May, moves backed by independence referendums, although Kiev and western powers did not recognise them.
Ukrainian troops pushed back rebel positions in eastern Ukraine, but separatists then opened a new front on the coast, seizing the town of Novoazovsk and posing real threat to the strategic port of Mariupol.
Fighting at Donetsk airport broke a ceasefire agreed on 5 September, and there were other violations in eastern parts.
The airport finally fell to rebels in January 2015 after months of fighting, leaving scenes of desolation and destruction and affording separatists a potentially vital means of resupply.
Renewed clashes prompted France and Germany to attempt to broker an end to the fighting, although fears remain that Russian President Vladimir Putin is only entertaining the prospect to further his grander strategic aims.